When using the "recursively update submodules" option, as well as a specific refspec, it tries to apply the same refspec when fetching changes for the submodule, causing spurious errors in the log:

Checkout:test / /home/punkyb/hudson/amd64-lucid/workspace/test - hudson.remoting.Channel@61ae0436:slave-amd64-lucid
Using strategy: Default
Last Built Revision: Revision becbe8166b41940e842548f8dcc895ddafc67ceb (origin/release/1.2)
Checkout:test / /home/punkyb/hudson/amd64-lucid/workspace/test - hudson.remoting.LocalChannel@23226fe1
GitAPI created
Fetching changes from the remote Git repository
Fetching upstream changes from ssh://sourcecontrol/parent.git
[test] $ git fetch -t ssh://sourcecontrol/parent.git/parent.git refs/heads/featurebranch
[test] $ git ls-tree HEAD
Trying to fetch submodule into /home/punkyb/hudson/amd64-lucid/workspace/test/submodule
GitAPI created
Fetching upstream changes from ssh://sourcecontrol/submodule.git
[submodule] $ git fetch -t ssh://sourcecontrol/submodule.git refs/heads/featurebranch
Problem fetching from submodule submodule - could be unavailable. Continuing anyway