Merge branch 'rr/for-each-ref-decoration'

Add a few formatting directives to "git for-each-ref --format=...",
to paint them in color, etc.

* rr/for-each-ref-decoration:
  for-each-ref: avoid color leakage
  for-each-ref: introduce %(color:...) for color
  for-each-ref: introduce %(upstream:track[short])
  for-each-ref: introduce %(HEAD) asterisk marker
  t6300 (for-each-ref): don't hardcode SHA-1 hexes
  t6300 (for-each-ref): clearly demarcate setup

Documentation/git-for-each-ref.txt

@@ -91,7 +91,19 @@ objectname::
 upstream::
 	The name of a local ref which can be considered ``upstream''
 	from the displayed ref. Respects `:short` in the same way as
-	`refname` above.
+	`refname` above.  Additionally respects `:track` to show
+	"[ahead N, behind M]" and `:trackshort` to show the terse
+	version: ">" (ahead), "<" (behind), "<>" (ahead and behind),
+	or "=" (in sync).  Has no effect if the ref does not have
+	tracking information associated with it.
+
+HEAD::
+	'*' if HEAD matches current ref (the checked out branch), ' '
+	otherwise.
+
+color::
+	Change output color.  Followed by `:<colorname>`, where names
+	are described in `color.branch.*`.
 
 In addition to the above, for commit and tag objects, the header
 field names (`tree`, `parent`, `object`, `type`, and `tag`) can