Merge branch 'sg/complete-paths'

Merge branch 'sg/complete-paths'

Command line completion (in contrib/) learned to complete pathnames
for various commands better.

* sg/complete-paths:
  t9902-completion: exercise __git_complete_index_file() directly
  completion: don't return with error from __gitcomp_file_direct()
  completion: fill COMPREPLY directly when completing paths
  completion: improve handling quoted paths in 'git ls-files's output
  completion: remove repeated dirnames with 'awk' during path completion
  t9902-completion: ignore COMPREPLY element order in some tests
  completion: use 'awk' to strip trailing path components
  completion: let 'ls-files' and 'diff-index' filter matching paths
  completion: improve handling quoted paths on the command line
  completion: support completing non-ASCII pathnames
  completion: simplify prefix path component handling during path completion
  completion: move __git_complete_index_file() next to its helpers
  t9902-completion: add tests demonstrating issues with quoted pathnames