git-gui: Don't format the mode line of a diff.
git-gui: Don't format the mode line of a diff.

We sometimes see a mode line show up in a diff if the file mode was
changed.  But its not something we format specially.

Signed-off-by: Shawn O. Pearce <f01032651c12a22b2103346ba96b3b6b231f9d3c@spearce.org>
destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git