store: do not record file that are not part of a revlog in fncache

The fncache exist to list file to copy/stream when cloning a repository, it
should only contains file that are relevant for a revlog in such case. For
example, temporary file are not relevant.

So we now skip the addiction of non-relevant file to the fn-cache in the first place.

mercurial/store.py

@@ -732,8 +732,10 b' class _fncachevfs(vfsmod.proxyvfs):'
 
     def __call__(self, path, mode=b'r', *args, **kw):
         encoded = self.encode(path)
-        if mode not in (b'r', b'rb') and (
-            path.startswith(b'data/') or path.startswith(b'meta/')
+        if (
+            mode not in (b'r', b'rb')
+            and (path.startswith(b'data/') or path.startswith(b'meta/'))
+            and revlog_type(path) is not None
         ):
             # do not trigger a fncache load when adding a file that already is
             # known to exist.