upgrade pip detetcion in pip-rehash to accept multiple variations: (#3330)

- pip
- pipX
- pipX.Y
- * -m pip

Co-authored-by: Christian Fredrik Johnsen <christian@johnsen.no>

pyenv.d/exec/pip-rehash.bash

@@ -4,6 +4,9 @@ PYENV_REHASH_COMMAND="${PYENV_COMMAND##*/}"
 # Remove any version information, from e.g. "pip2" or "pip3.10".
 if [[ $PYENV_REHASH_COMMAND =~ ^(pip|easy_install)[23](\.[0-9]+)?$ ]]; then
   PYENV_REHASH_COMMAND="${BASH_REMATCH[1]}"
+# Check for ` -m pip ` in arguments
+elif [[ "$*" =~ [[:space:]]-m[[:space:]]pip[[:space:]] ]]; then
+  PYENV_REHASH_COMMAND="pip"
 fi
 
 if [ -x "${PYENV_PIP_REHASH_ROOT}/${PYENV_REHASH_COMMAND}" ]; then