Commit email and LDAP email don't match with hooks
When using LDAP groups, emails are downcased. The commit email also needs to be downcased during comparisons, otherwise the pre-receive hook will cause a failure if the user hasn't chosen to downcase his own Git user.email entry.
Refer to https://gitlab.com/gitlab-org/gitlab-ee/blob/master/lib/gitlab/ldap/access.rb#L108