advice: handle "rebase" in error_resolve_conflict()

This makes sure that we get a properly translated message rather than inserting the command (which we failed to translate) into a generic fallback message. The function is called indirectly via die_resolve_conflict() with fixed strings, and directly with the string obtained via action_name(), which in turn returns a string from a fixed set. Hence we know that the now covered set of strings is exhausitive, and will therefore BUG() out when encountering an unexpected string. We also know that all covered strings are actually used. Arguably, the above suggests that it would be cleaner to pass the command as an enum in the first place, but that's left for another time. Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>