mercurial: pass ui to extensions.load (issue5007)

extensions.load does need ui argument to print error if an extension
fails to load.

doc/gendoc.py

@@ -110,7 +110,7 b' def showdoc(ui):'
              "   :depth: 1\n\n")
 
     for extensionname in sorted(allextensionnames()):
-        mod = extensions.load(None, extensionname, None)
+        mod = extensions.load(ui, extensionname, None)
         ui.write(minirst.subsection(extensionname))
         ui.write("%s\n\n" % gettext(mod.__doc__))
         cmdtable = getattr(mod, 'cmdtable', None)

mercurial/help.py

@@ -149,8 +149,7 b' def topicmatch(ui, kw):'
     for name, docs in itertools.chain(
         extensions.enabled(False).iteritems(),
         extensions.disabled().iteritems()):
-        # extensions.load ignores the UI argument
-        mod = extensions.load(None, name, '')
+        mod = extensions.load(ui, name, '')
         name = name.rpartition('.')[-1]
         if lowercontains(name) or lowercontains(docs):
             # extension docs are already translated