read-cache.c: fix a couple more CE_REMOVE conversion

read-cache.c: fix a couple more CE_REMOVE conversion

It is a D/F conflict if you want to add "foo/bar" to the index
when "foo" already exists.  Also it is a conflict if you want to
add a file "foo" when "foo/bar" exists.

An exception is when the existing entry is there only to mark "I
used to be here but I am being removed".  This is needed for
operations such as "git read-tree -m -u" that update the index
and then reflect the result to the work tree --- we need to
remember what to remove somewhere, and we use the index for
that.  In such a case, an existing file "foo" is being removed
and we can create "foo/" directory and hang "bar" underneath it
without any conflict.

We used to use (ce->ce_mode == 0) to mark an entry that is being
removed, but (CE_REMOVE & ce->ce_flags) is used for that purpose
these days.  An earlier commit forgot to convert the logic in
the code that checks D/F conflict condition.

The old code knew that "to be removed" entries cannot be at
higher stage and actively checked that condition, but it was an
unnecessary check.  This patch removes the extra check as well.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>