When no other ref than a RegExp with a gerrit username or shardeduserid
pattern, the permission is not properly validated and repository access
is denied.
With change Iedf3022f6c, calling shortestExample on regexp+parameters
refs produces a reference that won't match the username or the
shardeduserid.
For a reference like : ^refs/heads/users/${username}/.+
we will have the following:
'refs/heads/users/user1/my_branch' vs
'refs/heads/users/_PLACEHOLDER_/my_branch'
When we remove shortestExample, we have to modify Regexp and
ExpandParameters to skip the regexp start anchor caracter when comparing
against the prefix, or to compare regexps themselves.
Bug: Issue 3340
Change-Id: Id6a890a91c5d6d954dab74694c2d3fd53c15897c
80f75734e7