[PATCH 2 of 7] color: cleanup 'debugcolor' logic

[Pierre-Yves David]

# HG changeset patch
# User Pierre-Yves David <pierre-yves.david at ens-lyon.org>
# Date 1488048194 -3600
#      Sat Feb 25 19:43:14 2017 +0100
# Node ID a6afcb4e81ed425c633c206f121c5820ac91b0b0
# Parent  7e3d17f7acca8f1f1ff7d15864990201a528e1cd
# EXP-Topic color
color: cleanup 'debugcolor' logic

Now that style are carried by the 'ui' object, we no longer need complicated
logic to restore the original style. We just need to copy the 'ui' and work on
the copied version.

diff --git a/mercurial/debugcommands.py b/mercurial/debugcommands.py
--- a/mercurial/debugcommands.py
+++ b/mercurial/debugcommands.py
@@ -357,26 +357,22 @@ def debugcolor(ui, repo, **opts):
         return _debugdisplaycolor(ui)
 
 def _debugdisplaycolor(ui):
-    oldstyle = ui._styles.copy()
-    try:
-        ui._styles.clear()
-        for effect in color._effects.keys():
-            ui._styles[effect] = effect
-        if ui._terminfoparams:
-            for k, v in ui.configitems('color'):
-                if k.startswith('color.'):
-                    ui._styles[k] = k[6:]
-                elif k.startswith('terminfo.'):
-                    ui._styles[k] = k[9:]
-        ui.write(_('available colors:\n'))
-        # sort label with a '_' after the other to group '_background' entry.
-        items = sorted(ui._styles.items(),
-                       key=lambda i: ('_' in i[0], i[0], i[1]))
-        for colorname, label in items:
-            ui.write(('%s\n') % colorname, label=label)
-    finally:
-        ui._styles.clear()
-        ui._styles.update(oldstyle)
+    ui = ui.copy()
+    ui._styles.clear()
+    for effect in color._effects.keys():
+        ui._styles[effect] = effect
+    if ui._terminfoparams:
+        for k, v in ui.configitems('color'):
+            if k.startswith('color.'):
+                ui._styles[k] = k[6:]
+            elif k.startswith('terminfo.'):
+                ui._styles[k] = k[9:]
+    ui.write(_('available colors:\n'))
+    # sort label with a '_' after the other to group '_background' entry.
+    items = sorted(ui._styles.items(),
+                   key=lambda i: ('_' in i[0], i[0], i[1]))
+    for colorname, label in items:
+        ui.write(('%s\n') % colorname, label=label)
 
 def _debugdisplaystyle(ui):
     ui.write(_('available style:\n'))