crucible drops the rename in patch files

When we add patches to crucible reviews that contain renames, like

diff --git a/two b/three
similarity index 64%
rename from two
rename to three
index 75e1778..15815dd 100644
--- a/two
+++ b/three
@@ -1,8 +1,8 @@
-File two.
+File three.
 This is a
 longer file

we expect that crucible will display this as a rename, along with the file modifications. Full patch attached.

However it instead shows this only as a modification of the file under the old name; the new name (`three`) doesn't show up anywhere in the review.

We need to review such changes, and we need to do it via patches as crucible basically fails to index our repository, and thus commit-based reviews aren't feasible. Letting the patch describe the move as separate additions and removal makes crucible show it as such, but that doesn't help to actually review the content modifications.