sequencer: DO NOT DIE

A fast-forward may fail e.g. when it would overwrite an untracked
file. We still must not exit() in that case: the sequencer is
supposedly providing a library function.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

sequencer.c

@@ -339,7 +339,7 @@ static int fast_forward_to(const unsigned char *to, const unsigned char *from,
 
 	read_cache();
 	if (checkout_fast_forward(from, to, 1))
-		exit(128); /* the callee should have complained already */
+		return 128; /* the callee should have complained already */
 
 	strbuf_addf(&sb, "%s: fast-forward", action_name(opts));