[PATCH] help: treat hg help pattern like hg help patterns

[timeless]

# HG changeset patch
# User timeless <timeless at mozdev.org>
# Date 1445023325 14400
#      Fri Oct 16 15:22:05 2015 -0400
# Node ID dbd326c55e98a081253ad6e6d2d8e453c06115fe
# Parent  e8f1b728591786143174515ea18089db0df4af90
help: treat hg help pattern like hg help patterns

diff --git a/mercurial/help.py b/mercurial/help.py
--- a/mercurial/help.py
+++ b/mercurial/help.py
@@ -513,12 +513,19 @@
             queries += [helpcmd]
         if not queries:
             queries = (helptopic, helpcmd, helpext, helpextcmd)
-        for f in queries:
-            try:
-                rst = f(name)
+        def findtopic(name, queries):
+            rst = None
+            for f in queries:
+                try:
+                    rst = f(name)
+                    break
+                except error.UnknownCommand:
+                    pass
+            return rst
+        for topic in [name, name + 's', name + 'es']:
+            rst = findtopic(topic, queries)
+            if rst:
                 break
-            except error.UnknownCommand:
-                pass
         else:
             if unknowncmd:
                 raise error.UnknownCommand(name)
diff --git a/tests/test-help.t b/tests/test-help.t
--- a/tests/test-help.t
+++ b/tests/test-help.t
@@ -450,6 +450,11 @@
   
   (use "hg help -v ad" to show built-in aliases and global options)
 
+Test singular help
+  $ hg help pattern |grep '^[^ ]'
+  File Name Patterns
+  """"""""""""""""""
+
 Test command without options
 
   $ hg help verify