diff: fix textconv error zombies
diff: fix textconv error zombies

To make the code simpler, run_textconv lumps all of its
error checking into one conditional. However, the
short-circuit means that an error in reading will prevent us
from calling finish_command, leaving a zombie child.
Clean up properly after errors.

Based-on-work-by: Jeff King <696e3fbcf235d40b6ea1ebd61c87cbea79d444e7@peff.net>
Signed-off-by: Johannes Sixt <fd432345609ae4d58c1aa629cb66ba96d1391622@kdbg.org>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git