File contents are not updated when a revision also renames the file

When a revision both renames a file and modifies it, bzr upload will rename the file on the server, but doesn't upload the changed file content.

$ echo "Test1" > file.txt

$ bzr add file.txt
added file.txt

$ bzr commit
Committing to: /tmp/bzr-test/
added file.txt
Committed revision 1.

$ bzr upload sftp://xxx
No uploaded revision id found, switching to full upload
Uploading file.txt

$ bzr mv file.txt test.txt
file.txt => test.txt

$ echo "Test2" >> file.txt

$ bzr commit
Committing to: /tmp/bzr-test/
modified and renamed file.txt => test.txt
Committed revision 2.

$ bzr upload
Renaming file.txt to test.txt

# The file on the server is now named test.txt, but still contains only the line "Test1"