vcs: remove non-sensical conditional block

__get_action can only return "pull" or "push"; any other value is an
error on our end. And indeed, if not, the old code would crash further
down in the function (under "CHECK LOCKING") because the "user" local
variable was not assigned.

This also corrects the comment that incorrectly suggests the perm check
is only relevant for anonymous access.

The relevant code is duplicated between Hg and Git... and thus also
this change.

(Diff becomes clearer if whitespace changes are ignored.)