I'm not precisely sure when the "--progress" option was added to the "git fetch" command, but I know that it was not supported in version 1.7.0.4. I know it is supported in version 1.8.5.2, so I wouldn't be surprised if it was added to version 1.8 of the git client binary.

My preference would be a workaround similar to what was added when "git clone" started specifying the "-progress" option. Namely a check for the git binary version prior to attempting to use the "-progress" option. See JENKINS-9635.