narrowspec: replace one recursion-avoidance hack with another

When updating the working copy narrowspec, we call context.walk() in
order to find which files to update the working copy
with. context.walk() calls repo.narrowmatch(). In order to avoid
infinite recursion in this case, we have a hack that assigns the new
values for repo.narrowpats and repo._narrowmatch. However, doing that
of course breaks future invalidation of those properties (they're
@storecache'd). Let's instead avoid the infinite recursion by setting
a flag on the repo instance when we're updating the working copy.

Differential Revision: https://phab.mercurial-scm.org/D6468

mercurial/narrowspec.py

@@ -262,6 +262,9 b' def _writeaddedfiles(repo, pctx, files):'
                        mctx=repo['.'], overwrite=False)
 
 def checkworkingcopynarrowspec(repo):
+    # Avoid infinite recursion when updating the working copy
+    if getattr(repo, '_updatingnarrowspec', False):
+        return
     storespec = repo.svfs.tryread(FILENAME)
     wcspec = repo.vfs.tryread(DIRSTATE_FILENAME)
     if wcspec != storespec:
@@ -276,6 +279,7 b' def updateworkingcopy(repo, assumeclean='
     """
     oldspec = repo.vfs.tryread(DIRSTATE_FILENAME)
     newspec = repo.svfs.tryread(FILENAME)
+    repo._updatingnarrowspec = True
 
     oldincludes, oldexcludes = parseconfig(repo.ui, oldspec)
     newincludes, newexcludes = parseconfig(repo.ui, newspec)
@@ -305,10 +309,9 b' def updateworkingcopy(repo, assumeclean='
     for f in clean + trackeddirty:
         ds.drop(f)
 
-    repo.narrowpats = newincludes, newexcludes
-    repo._narrowmatch = newmatch
     pctx = repo['.']
     newfiles = [f for f in pctx.manifest().walk(addedmatch) if f not in ds]
     for f in newfiles:
         ds.normallookup(f)
     _writeaddedfiles(repo, pctx, newfiles)
+    repo._updatingnarrowspec = False