Attempting to sync into a workspace that contains '@' in the path fails:

p4 client -i

Error in client specification.
Embedded special characters (*, %%, #, @) not allowed in 'd:\jenkins\workspace\workflow_test_parallel@2'.

This is particularly an issue for workflow-plugin as it tends to append '@' to workspace paths such as the path used by the 'Store DSL script in SCM' ('@script'), and the second and later workspaces for a particular build script on a node ('@2', '@3', ...)