changing-files: always use `mark_touched` to update the touched set

We use this function internally too because that will make cache invalidation
simpler.

Differential Revision: https://phab.mercurial-scm.org/D9111

mercurial/metadata.py

@@ -84,7 +84,7 b' class ChangingFiles(object):'
 
     def mark_added(self, filename):
         self._added.add(filename)
-        self._touched.add(filename)
+        self.mark_touched(filename)
 
     def update_added(self, filenames):
         for f in filenames:
@@ -102,7 +102,7 b' class ChangingFiles(object):'
 
     def mark_merged(self, filename):
         self._merged.add(filename)
-        self._touched.add(filename)
+        self.mark_touched(filename)
 
     def update_merged(self, filenames):
         for f in filenames:
@@ -146,7 +146,7 b' class ChangingFiles(object):'
 
     def mark_removed(self, filename):
         self._removed.add(filename)
-        self._touched.add(filename)
+        self.mark_touched(filename)
 
     def update_removed(self, filenames):
         for f in filenames: