Activate a virtualenv of current version if specified version is not a virtualenv

```sh
% pyenv versions
  system
* miniconda3-3.16.0 (set by PYENV_VERSION environment variable)
  miniconda3-3.16.0/envs/venv
% pyenv activate venv
pyenv-virtualenv: deactivate miniconda3-3.16.0
pyenv-virtualenv: activate miniconda3-3.16.0/envs/venv
```

bin/pyenv-sh-activate

@@ -81,11 +81,21 @@ if [ -n "${VIRTUAL_ENV}" ] && [[ "${VIRTUAL_ENV}" != "${PYENV_ROOT}/versions/"*
 fi
 
 if ! pyenv-virtualenv-prefix "${venv}" 1>/dev/null 2>&1; then
-  if [ -z "${QUIET}" ]; then
+  # fallback to virtualenv of current version
-    echo "pyenv-virtualenv: version \`${venv}' is not a virtualenv" 1>&2
+  OLDIFS="$IFS"
+  IFS=: current_versions=($(pyenv-version-name))
+  IFS="$OLDIFS"
+  new_venv="${current_versions%/envs/*}/envs/${venv}"
+  if pyenv-virtualenv-prefix "${new_venv}" 1>/dev/null 2>&1; then
+    venv="${new_venv}"
+    versions[0]="${new_venv}"
+  else
+    if [ -z "${QUIET}" ]; then
+      echo "pyenv-virtualenv: version \`${venv}' is not a virtualenv" 1>&2
+    fi
+    echo "false"
+    exit 1
   fi
-  echo "false"
-  exit 1
 fi
 
 # exit as error if there are multiple virtualenvs

test/activate.bats

@@ -27,11 +27,6 @@ setup() {
 
   PYENV_SHELL="bash" PYENV_VERSION="venv" run pyenv-sh-activate
 
-  unstub pyenv-version-name
-  unstub pyenv-virtualenv-prefix
-  unstub pyenv-prefix
-  stub pyenv-sh-deactivate
-
   assert_success
   assert_output <<EOS
 deactivated
@@ -41,6 +36,11 @@ pyenv-virtualenv: prompt changing will be removed from future release. configure
 export _OLD_VIRTUAL_PS1="\${PS1}";
 export PS1="(venv) \${PS1}";
 EOS
+
+  unstub pyenv-version-name
+  unstub pyenv-virtualenv-prefix
+  unstub pyenv-prefix
+  unstub pyenv-sh-deactivate
 }
 
 @test "activate virtualenv from current version (verbose)" {
@@ -53,11 +53,6 @@ EOS
 
   PYENV_SHELL="bash" PYENV_VERSION="venv" run pyenv-sh-activate --verbose
 
-  unstub pyenv-version-name
-  unstub pyenv-virtualenv-prefix
-  unstub pyenv-prefix
-  unstub pyenv-sh-deactivate
-
   assert_success
   assert_output <<EOS
 deactivated
@@ -67,6 +62,11 @@ pyenv-virtualenv: prompt changing will be removed from future release. configure
 export _OLD_VIRTUAL_PS1="\${PS1}";
 export PS1="(venv) \${PS1}";
 EOS
+
+  unstub pyenv-version-name
+  unstub pyenv-virtualenv-prefix
+  unstub pyenv-prefix
+  unstub pyenv-sh-deactivate
 }
 
 @test "activate virtualenv from current version (without pyenv-virtualenv-init)" {
@@ -79,11 +79,6 @@ EOS
 
   PYENV_SHELL="bash" PYENV_VERSION="venv" run pyenv-sh-activate
 
-  unstub pyenv-version-name
-  unstub pyenv-virtualenv-prefix
-  unstub pyenv-prefix
-  unstub pyenv-sh-deactivate
-
   assert_success
   assert_output <<EOS
 # Load pyenv-virtualenv automatically by adding
@@ -100,6 +95,11 @@ pyenv-virtualenv: prompt changing will be removed from future release. configure
 export _OLD_VIRTUAL_PS1="\${PS1}";
 export PS1="(venv) \${PS1}";
 EOS
+
+  unstub pyenv-version-name
+  unstub pyenv-virtualenv-prefix
+  unstub pyenv-prefix
+  unstub pyenv-sh-deactivate
 }
 
 @test "activate virtualenv from current version (fish)" {
@@ -112,11 +112,6 @@ EOS
 
   PYENV_SHELL="fish" PYENV_VERSION="venv" run pyenv-sh-activate
 
-  unstub pyenv-version-name
-  unstub pyenv-virtualenv-prefix
-  unstub pyenv-prefix
-  unstub pyenv-sh-deactivate
-
   assert_success
   assert_output <<EOS
 deactivated
@@ -124,6 +119,11 @@ pyenv-virtualenv: activate venv
 setenv VIRTUAL_ENV "${PYENV_ROOT}/versions/venv";
 pyenv-virtualenv: prompt changing not work for fish.
 EOS
+
+  unstub pyenv-version-name
+  unstub pyenv-virtualenv-prefix
+  unstub pyenv-prefix
+  unstub pyenv-sh-deactivate
 }
 
 @test "activate virtualenv from current version (fish) (without pyenv-virtualenv-init)" {
@@ -136,11 +136,6 @@ EOS
 
   PYENV_SHELL="fish" PYENV_VERSION="venv" run pyenv-sh-activate
 
-  unstub pyenv-version-name
-  unstub pyenv-virtualenv-prefix
-  unstub pyenv-prefix
-  unstub pyenv-sh-deactivate
-
   assert_success
   assert_output <<EOS
 # Load pyenv-virtualenv automatically by adding
@@ -155,6 +150,11 @@ setenv PYENV_ACTIVATE_SHELL 1;
 setenv VIRTUAL_ENV "${PYENV_ROOT}/versions/venv";
 pyenv-virtualenv: prompt changing not work for fish.
 EOS
+
+  unstub pyenv-version-name
+  unstub pyenv-virtualenv-prefix
+  unstub pyenv-prefix
+  unstub pyenv-sh-deactivate
 }
 
 @test "activate virtualenv from command-line argument" {
@@ -166,10 +166,6 @@ EOS
 
   PYENV_SHELL="bash" PYENV_VERSION="venv" run pyenv-sh-activate "venv27"
 
-  unstub pyenv-virtualenv-prefix
-  unstub pyenv-prefix
-  unstub pyenv-sh-deactivate
-
   assert_success
   assert_output <<EOS
 deactivated
@@ -181,6 +177,10 @@ pyenv-virtualenv: prompt changing will be removed from future release. configure
 export _OLD_VIRTUAL_PS1="\${PS1}";
 export PS1="(venv27) \${PS1}";
 EOS
+
+  unstub pyenv-virtualenv-prefix
+  unstub pyenv-prefix
+  unstub pyenv-sh-deactivate
 }
 
 @test "activate virtualenv from command-line argument (without pyenv-virtualenv-init)" {
@@ -192,10 +192,6 @@ EOS
 
   PYENV_SHELL="bash" PYENV_VERSION="venv" run pyenv-sh-activate "venv27"
 
-  unstub pyenv-virtualenv-prefix
-  unstub pyenv-prefix
-  unstub pyenv-sh-deactivate
-
   assert_success
   assert_output <<EOS
 # Load pyenv-virtualenv automatically by adding
@@ -212,6 +208,10 @@ pyenv-virtualenv: prompt changing will be removed from future release. configure
 export _OLD_VIRTUAL_PS1="\${PS1}";
 export PS1="(venv27) \${PS1}";
 EOS
+
+  unstub pyenv-virtualenv-prefix
+  unstub pyenv-prefix
+  unstub pyenv-sh-deactivate
 }
 
 @test "activate virtualenv from command-line argument (fish)" {
@@ -223,10 +223,6 @@ EOS
 
   PYENV_SHELL="fish" PYENV_VERSION="venv" run pyenv-sh-activate "venv27"
 
-  unstub pyenv-virtualenv-prefix
-  unstub pyenv-prefix
-  unstub pyenv-sh-deactivate
-
   assert_success
   assert_output <<EOS
 deactivated
@@ -236,6 +232,10 @@ setenv PYENV_ACTIVATE_SHELL 1;
 setenv VIRTUAL_ENV "${PYENV_ROOT}/versions/venv27";
 pyenv-virtualenv: prompt changing not work for fish.
 EOS
+
+  unstub pyenv-virtualenv-prefix
+  unstub pyenv-prefix
+  unstub pyenv-sh-deactivate
 }
 
 @test "activate virtualenv from command-line argument (fish) (without pyenv-virtualenv-init)" {
@@ -247,10 +247,6 @@ EOS
 
   PYENV_SHELL="fish" PYENV_VERSION="venv" run pyenv-sh-activate "venv27"
 
-  unstub pyenv-virtualenv-prefix
-  unstub pyenv-prefix
-  unstub pyenv-sh-deactivate
-
   assert_success
   assert_output <<EOS
 # Load pyenv-virtualenv automatically by adding
@@ -265,6 +261,10 @@ setenv PYENV_ACTIVATE_SHELL 1;
 setenv VIRTUAL_ENV "${PYENV_ROOT}/versions/venv27";
 pyenv-virtualenv: prompt changing not work for fish.
 EOS
+
+  unstub pyenv-virtualenv-prefix
+  unstub pyenv-prefix
+  unstub pyenv-sh-deactivate
 }
 
 @test "unset invokes deactivate" {
@@ -275,16 +275,18 @@ EOS
 
   run pyenv-sh-activate --unset
 
-  unstub pyenv-sh-deactivate
-
   assert_success
   assert_output <<EOS
 deactivated
 EOS
+
+  unstub pyenv-sh-deactivate
 }
 
 @test "should fail if the version is not a virtualenv" {
   stub pyenv-virtualenv-prefix "3.3.3 : false"
+  stub pyenv-version-name " : echo 3.3.3"
+  stub pyenv-virtualenv-prefix "3.3.3/envs/3.3.3 : false"
 
   run pyenv-sh-activate "3.3.3"
 
@@ -293,19 +295,25 @@ EOS
 pyenv-virtualenv: version \`3.3.3' is not a virtualenv
 false
 EOS
+
+  unstub pyenv-virtualenv-prefix
+  unstub pyenv-version-name
 }
 
 @test "should fail if the version is not a virtualenv (quiet)" {
   stub pyenv-virtualenv-prefix "3.3.3 : false"
+  stub pyenv-version-name " : echo 3.3.3"
+  stub pyenv-virtualenv-prefix "3.3.3/envs/3.3.3 : false"
 
   run pyenv-sh-activate --quiet "3.3.3"
 
-  unstub pyenv-virtualenv-prefix
-
   assert_failure
   assert_output <<EOS
 false
 EOS
+
+  unstub pyenv-virtualenv-prefix
+  unstub pyenv-version-name
 }
 
 @test "should fail if there are multiple versions" {
@@ -314,13 +322,13 @@ EOS
 
   run pyenv-sh-activate "venv" "venv27"
 
-  unstub pyenv-virtualenv-prefix
-
   assert_failure
   assert_output <<EOS
 pyenv-virtualenv: cannot activate multiple versions at once: venv venv27
 false
 EOS
+
+  unstub pyenv-virtualenv-prefix
 }
 
 @test "should fail if there are multiple virtualenvs (quiet)" {
@@ -329,18 +337,20 @@ EOS
 
   run pyenv-sh-activate --quiet "venv" "venv27"
 
-  unstub pyenv-virtualenv-prefix
-
   assert_failure
   assert_output <<EOS
 false
 EOS
+
+  unstub pyenv-virtualenv-prefix
 }
 
 @test "should fail if the first version is not a virtualenv" {
   export PYENV_VIRTUALENV_INIT=1
 
   stub pyenv-virtualenv-prefix "2.7.10 : false"
+  stub pyenv-version-name " : echo 2.7.10"
+  stub pyenv-virtualenv-prefix "2.7.10/envs/2.7.10 : false"
 
   run pyenv-sh-activate "2.7.10" "venv27"
 
@@ -349,6 +359,9 @@ EOS
 pyenv-virtualenv: version \`2.7.10' is not a virtualenv
 false
 EOS
+
+  unstub pyenv-virtualenv-prefix
+  unstub pyenv-version-name
 }
 
 @test "activate if the first virtualenv is a virtualenv" {
@@ -361,10 +374,6 @@ EOS
 
   run pyenv-sh-activate "venv27" "2.7.10"
 
-  unstub pyenv-sh-deactivate
-  unstub pyenv-virtualenv-prefix
-  unstub pyenv-prefix
-
   assert_success
   assert_output <<EOS
 deactivated
@@ -376,6 +385,10 @@ pyenv-virtualenv: prompt changing will be removed from future release. configure
 export _OLD_VIRTUAL_PS1="\${PS1}";
 export PS1="(venv27) \${PS1}";
 EOS
+
+  unstub pyenv-sh-deactivate
+  unstub pyenv-virtualenv-prefix
+  unstub pyenv-prefix
 }
 
 @test "should fail if activate is invoked as a command" {