GitDownloadStrategy: fix typo'd parameter name

This should be "resource", not "resources", though it works anyway
because there is a also "resource" reader method.
reposurgeon 3.4

Details: http://freecode.com/projects/reposurgeon/releases/361564

Closes #26740.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
jenkins 1.551

Closes #26741.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
bottle: fail if there is no stable version.

Closes #26742.