Fix commit-msg hint to actually work

The change Ie4fcd0a73bd1cee12a052f38541f83aa8821c886 incorrectly
changed the command to suggest to install the commit-msg hook --
without the additional semicolon, the environment variable doesn't
seem to get set right. The braces are a cosmetic change, but nice
nonetheless.

Change-Id: Ia0a5c8f4304fb2402da8e7ea05a736bd762f3f49
Merge branch 'stable-2.6' into stable-2.7

* stable-2.6:
  Fix commit-msg hint to actually work
Merge branch 'stable-2.7' into stable-2.8

* stable-2.7:
  Fix commit-msg hint to actually work

Conflicts:
	gerrit-server/src/main/java/com/google/gerrit/server/git/validators/CommitValidators.java

Change-Id: I4b8d6c0d265d015f45fd31cb1fd284e32b7985eb