Git-merge-file is documented to return one of three exit
codes:
- zero means the merge was successful
- a negative number means an error occurred
- a positive number indicates the number of conflicts
Unfortunately, this all gets stuffed into an 8-bit return
code. Which means that if you have 256 conflicts, this wraps
to zero, and the merge appears to succeed (and commits a
blob full of conflict-marker cruft!).
This patch clamps the return value to a maximum of 127,
which we should be able to safely represent everywhere. This
also leaves 128-255 for other values. Shells (and some parts
of git) will typically represent signal death as 128 plus
the signal number. And negative values are typically coerced
to an 8-bit unsigned value (so "return -1" ends up as 255).
Technically negative returns have the same problem (e.g.,
"-256" wraps back to 0), but this is not a problem in
practice, as the only negative value we use is "-1".
Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>