lfs: use the local store method for opening a blob

I noticed that when I cloned without updating and then turned around and pushed
that clone to an lfs server, it was only trying to find the blob in the local
store.

Writes to the dummyremote (file based store) use local.read(), which looks at
both the usercache and local store.

hgext/lfs/blobstore.py

@@ -262,9 +262,9 b' class _gitlfsremote(object):'
         request = util.urlreq.request(href)
         if action == 'upload':
             # If uploading blobs, read data from local blobstore.
-            with localstore.vfs(oid) as fp:
+            with localstore.open(oid) as fp:
                 _verifyfile(oid, fp)
-            request.data = filewithprogress(localstore.vfs(oid), None)
+            request.data = filewithprogress(localstore.open(oid), None)
             request.get_method = lambda: 'PUT'
 
         for k, v in headers:

tests/test-lfs-test-server.t

@@ -38,7 +38,11 b''
   $ echo THIS-IS-LFS > a
   $ hg commit -m a -A a
 
+A push can be serviced directly from the usercache if it isn't in the local
+store.
+
   $ hg init ../repo2
+  $ mv .hg/store/lfs .hg/store/lfs_
   $ hg push ../repo2 -v
   pushing to ../repo2
   searching for changes
@@ -54,6 +58,7 b''
   adding file changes
   added 1 changesets with 1 changes to 1 files
   calling hook pretxnchangegroup.lfs: hgext.lfs.checkrequireslfs
+  $ mv .hg/store/lfs_ .hg/store/lfs
 
 Clear the cache to force a download
   $ rm -rf `hg config lfs.usercache`