extensions: don't get confused by aliasing between "foo" and "hgext.foo"

mercurial/extensions.py

@@ -24,7 +24,11 b' def find(name):'
         raise KeyError(name)
 
 def load(ui, name, path):
-    if name in _extensions:
+    if name.startswith('hgext.'):
+        shortname = name[6:]
+    else:
+        shortname = name
+    if shortname in _extensions:
         return
     if path:
         # the module will be loaded in sys.modules
@@ -49,7 +53,7 b' def load(ui, name, path):'
             mod = importh("hgext.%s" % name)
         except ImportError:
             mod = importh(name)
-    _extensions[name] = mod
+    _extensions[shortname] = mod
 
     uisetup = getattr(mod, 'uisetup', None)
     if uisetup: