[GUILT] Preventing "git push" when guilt patches are applied

[Per Cederqvist <cederp@opera.com>]

I have by accident done "git push" when I intended to write "guilt
push" a couple of times.  If there are guilt patches applied when I do
this the result is that (part of) my half-finished patch series is
pushed to the master branch.  That is of course not good.

TopGit avoids this issue since I'm on a separate branch when patches
are applied.

Mercurial Queues prevents this.  If I try to do "hg push" with a patch
applied, I get this error:

 > pushing to /home/cederp/pushstop/hgmaster
 > abort: source has mq patches applied

I'd like to add something similar to Guilt, to avoid making this
mistake ever again.  (It is quite embarrassing to clean up after you
push a couple of half-baked patches.)  But I don't know how the
feature should be designed.  Some ideas:

  - Add pre-push hooks to Git, like the one proposed back in 2008 in
    <http://thread.gmane.org/gmane.comp.version-control.git/92900>.
    Have Guilt automatically install a pre-push hook that produces an
    error message if Guilt patches are applied.

  - Have Guilt create a status file (maybe .git/PUSH_FORBIDDEN)
    whenever patches are applied, and remove the file when it pops all
    patches.  The file would contain the following text: "Refusing to
    push while guilt patches are applied.  Hint: see 'guilt -h
    commit'."  Have "git push" check for that file, and print its
    contents if it exists.  (Or should "git push" check for any file
    matching the glob pattern ".git/PUSH_FORBIDDEN.*" and Guilt create
    .git/PUSH_FORBIDDEN.Guilt so that this mechanism is more
    extensible?)

  - Have Guilt remove all remotes when patches are pushed, and restore
    them when all patches are popped.  (I don't like this idea; there
    are too many things that could go wrong.  But it would be possible
    to implement without doing any changes to Git itself.)

I hope the Git community can come up with a better design for this
feature.

     /ceder