Fix SDK repo to prevent mixing different targets.

This makes sure that sdk-repo-*.zip doesn't exist to
avoid merging into an existing one.

Also fix a warning when generating the repo.xml files.

(cherry picked from commit 4df9f469f710b4eedde9020f7a35534a795edfb1)

Change-Id: Ifeb1234cacf121458bda9d869d7e5df5b5a19673
2 files changed