Merge branch 'ib/rev-parse-parseopt-argh'

Teaches the "rev-parse --parseopt" mechanism used by scripted
Porcelains to parse command line options and give help text how to
supply argv-help (the placeholder string for an option parameter,
e.g. "key-id" in "--gpg-sign=<key-id>").

* ib/rev-parse-parseopt-argh:
  t1502: protect runs of SPs used in the indentation
  rev-parse --parseopt: option argument name hints