extensions: remove dead code

enabled used to be a boolean, and somehow that bit of code inadvertently
slipped through during a refactoring. Effectively dead code, as the
condition can never be triggered.

mercurial/extensions.py

@@ -166,10 +166,6 b' def disabled():'
 
 def enabled():
     '''return a dict of {name: desc} of extensions, and the max name length'''
-
-    if not enabled:
-        return {}, 0
-
     exts = {}
     maxlength = 0
     exthelps = []