build not active when using copy_from

[Jamal]

when creating a job form a copy, the build option is not enabled.
server.copy_job("old_job","my_job")
server.enable_job("my_job") # not working the build button is not visible

#so either go to the GUI and select "configure" and "Save" or :
server.disable_job("my_job")
server.enable_job("my_job") # now works