[PATCH 2 of 2 V4] color: fallback and test label as an effect

[Sean Farley]

# HG changeset patch
# User Sean Farley <sean.michael.farley at gmail.com>
# Date 1396903047 18000
#      Mon Apr 07 15:37:27 2014 -0500
# Node ID c3f05ce58c1a48c70a6d998a6fe64533a28fb262
# Parent  fe252f8b05c6a0e3b3ad4ed54d90c5bac07c0d6b
color: fallback and test label as an effect

With this changeset, we can now send a color name directly to the label
function, e.g.

$ hg log -r . -T "{label('red', node|short)}\n"

diff --git a/hgext/color.py b/hgext/color.py
--- a/hgext/color.py
+++ b/hgext/color.py
@@ -380,10 +380,12 @@ class colorui(uimod.ui):
         effects = []
         for l in label.split():
             s = _styles.get(l, '')
             if s:
                 effects.append(s)
+            elif valideffect(l):
+                effects.append(l)
         effects = ' '.join(effects)
         if effects:
             return '\n'.join([render_effects(s, effects)
                               for s in msg.split('\n')])
         return msg