Merge branch 'jk/interpret-branch-name-fix'

Fix a handful of bugs around interpreting $branch@{upstream}
notation and its lookalike, when $branch part has interesting
characters, e.g. "@", and ":".

* jk/interpret-branch-name-fix:
  interpret_branch_name: find all possible @-marks
  interpret_branch_name: avoid @{upstream} past colon
  interpret_branch_name: always respect "namelen" parameter
  interpret_branch_name: rename "cp" variable to "at"
  interpret_branch_name: factor out upstream handling

diff --cc sha1_name.c
Simple merge