t3701: Editing a split hunk in an "add -p" session

t3701: Editing a split hunk in an "add -p" session

Arnaud Lacombe reported that with the recent change to reject overlapping
hunks fed to "git apply", the edit mode of an "add -p" session that lazily
feeds overlapping hunks without coalescing adjacent ones claim that the
patch does not apply.  Expose the problem to be fixed.

Cf. http://thread.gmane.org/gmane.comp.version-control.git/170685/focus=171000

Signed-off-by: Junio C Hamano <gitster@pobox.com>