CLI -P containing equals sign fails to parse properly

[arcivanov]

$ pyb -v -X -P gevent_version===1.4.0
Traceback (most recent call last):
  File "/home/arcivanov/.pyenv/versions/geventmp/bin/pyb", line 8, in <module>
    sys.exit(main())
  File "/home/arcivanov/.pyenv/versions/geventmp/lib/python3.7/site-packages/pybuilder/cli.py", line 406, in main
    options, arguments = parse_options(args)
  File "/home/arcivanov/.pyenv/versions/geventmp/lib/python3.7/site-packages/pybuilder/cli.py", line 225, in parse_options
    key, val = pair.split("=")
ValueError: too many values to unpack (expected 2)