git-gui: Do not offer to stage three-way diff hunks into the index

git-apply does not accept a patch that was generated as a three-way
combined diff format such as we see during merge conflicts.  If we
get such a diff in our diff viewer and try to send it to git-apply
it just errors out and the user is left confused wondering why they
cannot stage that hunk.

Instead of feeding a known to be unacceptable hunk to git-apply we
now just disable the stage/unstage context menu option if the hunk
came from a three way diff.  The user may still be confused about
why they cannot work with a combined diff, but at least they are
only confused as to why git-gui is not offering them the action.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
1 file changed
tree: fec2e9c14273135ca42b767048f598fda1fd7dc6
  1. .gitignore
  2. GIT-VERSION-GEN
  3. Makefile
  4. git-gui.sh
  5. lib/