remotefilelog: fix crash on `hg addremove` of added-but-deleted file

If you `hg add` a file and then delete it from disk, and then run `hg
addremove`, the file ends up in the "removed" set that gets passed to
the findrenames() override. We then crash because the file is not in
the working copy parent. This patch fixes that.

Differential Revision: https://phab.mercurial-scm.org/D6194

hgext/remotefilelog/__init__.py

@@ -478,9 +478,10 b' def onetimeclientsetup(ui):'
     def findrenames(orig, repo, matcher, added, removed, *args, **kwargs):
         if isenabled(repo):
             files = []
-            parentctx = repo['.']
+            pmf = repo['.'].manifest()
             for f in removed:
-                files.append((f, hex(parentctx.filenode(f))))
+                if f in pmf:
+                    files.append((f, hex(pmf[f])))
             # batch fetch the needed files from the server
             repo.fileservice.prefetch(files)
         return orig(repo, matcher, added, removed, *args, **kwargs)

tests/test-remotefilelog-prefetch.t

@@ -197,6 +197,9 b''
   $ mv x x2
   $ mv y y2
   $ mv z z2
+  $ echo a > a
+  $ hg add a
+  $ rm a
   $ clearcache
   $ hg addremove -s 50 > /dev/null
   3 files fetched over 1 fetches - (3 misses, 0.00% hit ratio) over * (glob)