Revert "Fix local variable 'root_uuid' ref before assign"

This reverts commit 30bc1ef250f0230a9a1f562cd51b0f57d4a35912, which
fixed a NameError but introduced a new bug in the deploy process
that could cause silent failures in a deploy. Instead, we should
log a more descriptive error and allow the exception to be raised.

Change-Id: I0221984ce4f7c406990315ef820d9ce63fc6e015
Merge "Revert "Fix local variable 'root_uuid' ref before assign""