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.

mercurial/debugcommands.py

@@ -357,26 +357,22 b' 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'))