We can discover the next build number Jenkins will use for a particular
job using get_job_info(), but there's currently no way through
python-jenkins to set the next build number. This change introduces
the set_next_build_number() method which, given a job name and a
desired number, sets the next build number of the named job to the
given number.
Limitations: Jenkins enforces that build numbers must be monotonically
increasing, but gives no indication of an error; it simply ignores the
offending value.
Change-Id: I23b5a84b7ea37d66bf778a89343e3c81ffa9ceb6
244b4fed30