The update codepath would trigger:
Exception: UnboundLocalError: local variable 'svnfetchcmd' referenced before assignment
Fix this so the code functions as intended in both fetch and update cases.
[YOCTO #13798]
(Bitbake rev: 16c4e930ff37ea6eac2ac0cb2197908ce3a1cc53)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>