Merge branch 'wc/find-commit-with-pattern-on-detached-head'

"git rev-parse ':/substring'" did not consider the history leading
only to HEAD when looking for a commit with the given substring,
when the HEAD is detached.  This has been fixed.

* wc/find-commit-with-pattern-on-detached-head:
  sha1-name.c: for ":/", find detached HEAD commits

diff --cc Documentation/revisions.txt
Simple merge

diff --cc sha1-name.c
Simple merge

diff --cc t/t4208-log-magic-pathspec.sh
Simple merge