gitolite: Set default branch on first push

The non-core feature 'symbolic-ref' that ships with gitolite opens a
bigger hole than I would intend to (in the form of allowing arbitrary
git-symbolic-ref commands to be executed).

As an alternative, a post-git gitolite trigger is added.  Its only
purpose at the moment is to check on the state of HEAD following any
pushes.

Under normal circumstances, HEAD will point to a valid branch, or on a
first push, the master branch will be provided, validating HEAD.  If
after the first push, there is no branch called master, we assume the
creator wishes to use another name for the default branch, and so will
update the ref if doing so is unambiguous (there is only one other
branch).  If multiple non-master branches are present in this case, a
warning is issued, and HEAD is left invalid, awaiting a later push to
master.

This _should_ only be an issue for the first push.  Once HEAD refers to
a valid branch (of any name), this action is bypassed going forward.

Signed-off-by: Malfurious <m@lfurio.us>

0 files changed, 0 insertions, 0 deletions