extensions: copy extra __dict__ of original function

Future patches will make @command decorator set properties such as "norepo" to
a function object. This patch makes sure these properties never be lost by
wrapcommand() or wrapfunction().

This change won't be crazy as the standard functools.wraps() copies __dict__.

mercurial/extensions.py

@@ -199,6 +199,7 b' def _updatewrapper(wrap, origfn):'
     '''Copy attributes to wrapper function'''
     wrap.__module__ = getattr(origfn, '__module__')
     wrap.__doc__ = getattr(origfn, '__doc__')
+    wrap.__dict__.update(getattr(origfn, '__dict__', {}))
 
 def wrapcommand(table, command, wrapper, synopsis=None, docstring=None):
     '''Wrap the command named `command' in table