Petr Baudis authored Jun 28, 2013 and Junio C Hamano committed Jul 01, 2013

"stash save" is about saving the local change to the working tree,
but also about restoring the state of the last commit to the working
tree.  When a local change is to turn a non-directory to a directory,
in order to restore the non-directory, everything in the directory
needs to be removed.

Which is fine when running "git stash save --include-untracked",
but without that option, untracked, newly created files in the
directory will have to be discarded, if the state you are restoring
to has a non-directory at the same path as the directory.

Introduce a safety valve to fail the operation in such case, using
the "ls-files --killed" which was designed for this exact purpose.

The "stash save" is stopped when untracked files need to be
discarded because their leading path ceased to be a directory, and
the user is required to pass --force to really have the data
removed.

Signed-off-by: Petr Baudis <pasky@ucw.cz>
Signed-off-by: Junio C Hamano <gitster@pobox.com>