Merge pull request #620 from yyuu/workaround-aria2c-stdout

Write remote content on stdout with `aria2c`

plugins/python-build/bin/python-build

@@ -340,7 +340,12 @@ http_head_aria2c() {
 }
 
 http_get_aria2c() {
-  aria2c -o "${2:--}" ${ARIA2_OPTS} "$1"
+  local out="${2:-$(mktemp "out.XXXXXX")}"
+  if aria2c --allow-overwrite=true -o "${out}" ${ARIA2_OPTS} "$1" >&4; then
+    [ -n "$2" ] || cat "${out}"
+  else
+    false
+  fi
 }
 
 http_head_curl() {