Add ui.patch option.

ui.patch overrides the default patch/gpatch command and options.

doc/hgrc.5.txt

@@ -432,6 +432,9 b' ui::'
   merge;;
     The conflict resolution program to use during a manual merge.
     Default is "hgmerge".
+  patch;;
+    command to use to apply patches. Look for 'gpatch' or 'patch' in PATH if
+    unset.
   quiet;;
     Reduce the amount of output printed.  True or False.  Default is False.
   remotecmd;;

mercurial/commands.py

@@ -881,8 +881,10 b' def debuginstall(ui):'
     # patch
     ui.status(_("Checking patch...\n"))
     path = os.environ.get('PATH', '')
-    patcher = util.find_in_path('gpatch', path,
-                                util.find_in_path('patch', path, None))
+    patcher = ui.config('ui', 'patch')
+    if not patcher:
+        patcher = util.find_in_path('gpatch', path,
+                                    util.find_in_path('patch', path, None))
     if not patcher:
         ui.write(_(" Can't find patch or gpatch in PATH\n"))
         ui.write(_(" (specify a patch utility in your .hgrc file)\n"))

mercurial/patch.py

@@ -293,11 +293,13 b' def patch(patchname, ui, strip=1, cwd=No'
         """patch and updates the files and fuzz variables"""
         fuzz = False
 
-        patcher = util.find_in_path('gpatch', os.environ.get('PATH', ''),
-                                    'patch')
         args = []
-        if util.needbinarypatch():
-            args.append('--binary')
+        patcher = ui.config('ui', 'patch')
+        if not patcher:
+            patcher = util.find_in_path('gpatch', os.environ.get('PATH', ''),
+                                        'patch')
+            if util.needbinarypatch():
+                args.append('--binary')
                                     
         if cwd:
             args.append('-d %s' % util.shellquote(cwd))