committablectx: simplify caching the status

Previously, workingctx had custom variables for the unknown, ignored, and clean
list of files of status. These then got moved to committablectx and, after the
refactoring of localrepo.status, are no longer needed. We, therefore, simplify
the whole mess.

As a bonus, we are able to remove the need for having 'assert'.

mercurial/context.py

@@ -892,14 +892,7 b' class committablectx(basectx):'
         if user:
             self._user = user
         if changes:
-            self._status = list(changes[:4])
-            self._unknown = changes[4]
-            self._ignored = changes[5]
-            self._clean = changes[6]
-        else:
-            self._unknown = None
-            self._ignored = None
-            self._clean = None
+            self._status = changes
 
         self._extra = {}
         if extra:
@@ -974,7 +967,7 b' class committablectx(basectx):'
 
         copied = self._repo.dirstate.copies()
         ff = self._flagfunc
-        modified, added, removed, deleted = self._status
+        modified, added, removed, deleted = self._status[:4]
         for i, l in (("a", added), ("m", modified)):
             for f in l:
                 orig = copied.get(f, f)
@@ -992,7 +985,7 b' class committablectx(basectx):'
 
     @propertycache
     def _status(self):
-        return self._repo.status()[:4]
+        return self._repo.status()
 
     @propertycache
     def _user(self):
@@ -1023,14 +1016,11 b' class committablectx(basectx):'
     def deleted(self):
         return self._status[3]
     def unknown(self):
-        assert self._unknown is not None  # must call status first
-        return self._unknown
+        return self._status[4]
     def ignored(self):
-        assert self._ignored is not None  # must call status first
-        return self._ignored
+        return self._status[5]
     def clean(self):
-        assert self._clean is not None  # must call status first
-        return self._clean
+        return self._status[6]
     def branch(self):
         return encoding.tolocal(self._extra['branch'])
     def closesbranch(self):
@@ -1395,20 +1385,10 b' class workingctx(committablectx):'
         listignored, listclean, listunknown = ignored, clean, unknown
         s = self._dirstatestatus(match=match, ignored=listignored,
                                  clean=listclean, unknown=listunknown)
-        modified, added, removed, deleted, unknown, ignored, clean = s
 
-        modified = self._filtersuspectsymlink(modified)
-
-        self._unknown = self._ignored = self._clean = None
-        if listunknown:
-            self._unknown = unknown
-        if listignored:
-            self._ignored = ignored
-        if listclean:
-            self._clean = clean
-        self._status = modified, added, removed, deleted
-
-        return modified, added, removed, deleted, unknown, ignored, clean
+        s[0] = self._filtersuspectsymlink(s[0])
+        self._status = s
+        return s
 
 
 class committablefilectx(basefilectx):