gitignore: add a config option

Summary:
gitignore could have performance issues stating .gitignore files everywhere.
That happens if watchman returns O(working copy) files. Add a config to
disable it as we're finding solutions.

Reviewed By: DurhamG

Differential Revision: D7482499

fbshipit-source-id: 4c9247b0318bf034c8e9af4b74c21110cc598714

mercurial/configitems.py

@@ -998,6 +998,9 @@ coreconfigitem('ui', 'formatjson',
 coreconfigitem('ui', 'formatted',
     default=None,
 )
+coreconfigitem('ui', 'gitignore',
+    default=False,
+)
 coreconfigitem('ui', 'graphnodetemplate',
     default=None,
 )

mercurial/dirstate.py

@@ -164,7 +164,10 @@ class dirstate(object):
     @rootcache('.hgignore')
     def _ignore(self):
         files = self._ignorefiles()
-        gitignore = matchmod.gitignorematcher(self._root, '')
+        if self._ui.configbool('ui', 'gitignore'):
+            gitignore = matchmod.gitignorematcher(self._root, '')
+        else:
+            gitignore = matchmod.nevermatcher(self._root, '')
         if not files:
             return gitignore
 

mercurial/help/config.txt

@@ -2084,6 +2084,9 @@ User interface controls.
     Encoding to try if it's not possible to decode the changelog using
     UTF-8. (default: ISO-8859-1)
 
+``gitignore``
+    Respect gitignore or not. (default: False)
+
 ``graphnodetemplate``
     The template used to print changeset nodes in an ASCII revision graph.
     (default: ``{graphnode}``)

tests/test-gitignore.t

@@ -1,4 +1,5 @@
   $ newrepo
+  $ setconfig ui.gitignore=1
 
   $ cat > .gitignore << EOF
   > *.tmp

tests/test-hgignore.t

@@ -3,9 +3,12 @@
 
 gitignore is used when there is no hgignore:
 
-  $ hg debugignore
+  $ hg debugignore --config ui.gitignore=1
   <gitignorematcher>
 
+  $ hg debugignore --config ui.gitignore=0
+  <nevermatcher>
+
 Issue562: .hgignore requires newline at end:
 
   $ touch foo
@@ -197,9 +200,12 @@ Test relative ignore path (issue4473):
   $ hg status .
   A b.o
 
-  $ hg debugignore
+  $ hg debugignore --config ui.gitignore=1
   <unionmatcher matchers=[<gitignorematcher>, <includematcher includes='(?:(?:|.*/)[^/]*(?:/|$))'>]>
 
+  $ hg debugignore
+  <unionmatcher matchers=[<nevermatcher>, <includematcher includes='(?:(?:|.*/)[^/]*(?:/|$))'>]>
+
   $ hg debugignore b.o
   b.o is ignored
   (ignore rule in $TESTTMP/ignorerepo/.hgignore, line 1: '*') (glob)