Merge branch 'pk/rebase-in-c-6-final' into pu

With "rebase -i" machinery being rewritten to C, with a different
interface between "rebase" proper and its backends, this and the
other topics need a bit more work to play with each other better.

This assumes that the meat of "rebase -i" and other backends will
stay to be written as shell scripts, and can be dot-sourced with
". git-rebase--$backend", but that assumption directly contradicts
with what the other GSoC project to rewrite "rebase -i" machinery
in C does, so neither topic is usable as they are without inter
topic coordination.

* pk/rebase-in-c-6-final:
  rebase: default to using the builtin rebase

Author: gitster

builtin/rebase.c

@@ -55,7 +55,7 @@ static int use_builtin_rebase(void)
 	cp.git_cmd = 1;
 	if (capture_command(&cp, &out, 6)) {
 		strbuf_release(&out);
-		return 0;
+		return 1;
 	}
 
 	strbuf_trim(&out);