dir.h documented quite clearly that DIR_SHOW_IGNORED and
DIR_SHOW_IGNORED_TOO are mutually exclusive, with a big comment to this
effect by the definition of both enum values. However, a command like
git clean -fx $DIR
would set both values for dir.flags. I _think_ it happened to work
because:
* As dir.h points out, DIR_KEEP_UNTRACKED_CONTENTS only takes effect
if DIR_SHOW_IGNORED_TOO is set.
* As coded, I believe DIR_SHOW_IGNORED would just happen to take
precedence over DIR_SHOW_IGNORED_TOO in the code as currently
constructed.
Which is a long way of saying "we just got lucky".
Fix clean.c to avoid setting these mutually exclusive values at the same
time, and add a check to dir.c that will throw a BUG() to prevent anyone
else from making this mistake.
Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>