[PATCH 3 of 3] color: change color of grep.rev label

[Jordi Gutiérrez Hermoso]

# HG changeset patch
# User Jordi Gutiérrez Hermoso <jordigh at octave.org>
# Date 1550263757 18000
#      Fri Feb 15 15:49:17 2019 -0500
# Node ID 07f0f1082c85076b6e0d0cb215fb34893170c11c
# Parent  9e2f595cf719f2dd863485067517f4f6c05dee73
color: change color of grep.rev label

GNU grep uses green for line numbers as we do, but I sometimes get a
bit confused when I do `hg grep --diff -n` and get both line numbers
and revisions and don't know which one is which.

A different colour can help.

diff --git a/mercurial/color.py b/mercurial/color.py
--- a/mercurial/color.py
+++ b/mercurial/color.py
@@ -77,7 +77,7 @@ except ImportError:
 _defaultstyles = {
     'grep.match': 'red bold',
     'grep.linenumber': 'green',
-    'grep.rev': 'green',
+    'grep.rev': 'blue',
     'grep.sep': 'cyan',
     'grep.filename': 'magenta',
     'grep.user': 'magenta',