fix build of 3.4-dev. append existing 3.4 at the last.

this is because `hg` (which is a dependency of *-dev build) might be
installed in existing pyenv versions.

plugins/python-build/bin/pyenv-install

@@ -152,9 +152,9 @@ fi
 # Python 3.4 installer requires an existing Python installation to run. An
 # unsatisfied local .python-version file can cause the installer to
 # fail.)
-if [ -z "${PYENV_VERSION}" ]; then
-  export PYENV_VERSION="$(pyenv global 2>/dev/null || true)"
-fi
+#if [ -z "${PYENV_VERSION}" ]; then
+#  export PYENV_VERSION="$(pyenv global 2>/dev/null || true)"
+#fi
 
 
 # Execute `before_install` hooks.

plugins/python-build/share/python-build/3.4-dev

@@ -1,7 +1,7 @@
 # Python 3.4 requires "python3.4" to be executable if it is in ${PATH}.
 if ! pyenv-which python3.4 1>/dev/null 2>&1; then
   if pyenv-whence python3.4 1>/dev/null 2>&1; then
-    export PYENV_VERSION="$(pyenv-whence python3.4 2>/dev/null | tail -1)"
+    export PYENV_VERSION="$(pyenv-version-name):$(pyenv-whence python3.4 2>/dev/null | tail -1)"
   fi
 fi