Handle extensions with defined but empty cmdtable

mercurial/commands.py

@@ -1395,6 +1395,8 b' def help_(ui, name=None, with_version=Fa'
         try:
             ct = mod.cmdtable
         except AttributeError:
+            ct = None
+        if not ct:
             ui.status(_('no commands defined\n'))
             return
 

tests/test-extension

@@ -53,3 +53,14 b" echo '[extensions]' > $HGRCPATH"
 echo "barfoo = $barfoopath" >> $HGRCPATH
 cd a
 hg foo
+
+cd ..
+cat > empty.py <<EOF
+'''empty cmdtable
+'''
+cmdtable = {}
+EOF
+emptypath=`pwd`/empty.py
+echo '[extensions]' > $HGRCPATH
+echo "empty = $emptypath" >> $HGRCPATH
+hg help empty

tests/test-extension.out

@@ -19,3 +19,6 b' ui.parentui isnot None'
 reposetup called for a
 ui == repo.ui
 Foo
+empty extension - empty cmdtable
+
+no commands defined