convert: make filemap renames consistently override revision renames

When the source repository had a revision renaming "$new -> $old",
but the filemap a "$old -> $new" rename, the converted revision could
use either $new (deleting the file) or $old (keeping the file) when
getting the file data, depending on the lexicographical order of
those names. So the resulting revision would leave some files
untouched (as expected), but delete others arbitrarely.

hgext/convert/filemap.py

@@ -348,12 +348,13 b' class filemap_source(converter_source):'
         # original filename in the rev part of the return value.
         changes, copies = self.base.getchanges(rev)
         newnames = {}
-        files = []
+        files = {}
         for f, r in changes:
             newf = self.filemapper(f)
-            if newf:
-                files.append((newf, (f, r)))
+            if newf and (newf != f or newf not in files):
+                files[newf] = (f, r)
                 newnames[f] = newf
+        files = sorted(files.items())
 
         ncopies = {}
         for c in copies:

tests/test-convert-filemap.t

@@ -375,3 +375,36 b' exercise incremental conversion at the s'
   |
   o  0 "addb" files: b
   
+
+filemap rename undoing revision rename
+
+  $ hg init renameundo
+  $ cd renameundo
+  $ echo 1 > a
+  $ echo 1 > c
+  $ hg ci -qAm add
+  $ hg mv -q a b/a
+  $ hg mv -q c b/c
+  $ hg ci -qm rename
+  $ echo 2 > b/a
+  $ echo 2 > b/c
+  $ hg ci -qm modify
+  $ cd ..
+
+  $ echo "rename b ." > renameundo.fmap
+  $ hg convert --filemap renameundo.fmap renameundo renameundo2
+  initializing destination renameundo2 repository
+  scanning source...
+  sorting...
+  converting...
+  2 add
+  1 rename
+  filtering out empty revision
+  repository tip rolled back to revision 0 (undo commit)
+  0 modify
+  $ glog -R renameundo2
+  o  1 "modify" files: a c
+  |
+  o  0 "add" files: a c
+  
+