This reverts commit bddf9de8f1.
When pyenv-auto-set-local-pyenv-version is set to 'on-visit then this
switched the python version when e.g. using jump to definition.
Helm seems to treat "!" specially in pattern matching, so having a ! in
the pattern string when traversing directories is problematic. This
change fixes#2737, because as far as I can tell "+" has no special
meaning in a helm pattern.
Of course, we can choose a different character, but I'm fond of "+" as
representing "more layers here".
