filter-branch: Remove broken and unnecessary summary of rewritten refs.

filter-branch: Remove broken and unnecessary summary of rewritten refs.

There was an attempt to list the refs that were rewritten by filtering
the output of 'git show-ref' for 'refs/original'. But it got the
grep argument wrong, which did not account for the SHA1 that is listed
before the ref.

Moreover, right before this summary is the loop that actually does the
rewriting, and the rewritten refs are listed there anyway. So this extra
summary is plainly too verbose.

Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>