Merge branch 'fix'

* fix:
  Document --short and --git-dir in git-rev-parse(1)
  git-rev-parse: Fix --short= option parsing
  Prevent git-upload-pack segfault if object cannot be found
  Abstract test_create_repo out for use in tests.
  Trap exit to clean up created directory if clone fails.

diff --cc rev-parse.c
Simple merge

diff --cc sha1_file.c
Simple merge