Release 1.2.13

[kwlzn]

docket:

• Fix handling of pre-release option. Fix handling of pre-release option. #424
• Patch sys module using pex_path from PEX-INFO metadata Improve PEX_PATH handling in pex.py #421

[kwlzn]

release is out on pypi. cc: @zvezdan @CMLivingston

[zvezdan]

Thanks a lot @kwlzn!

[CMLivingston]

Thanks @kwlzn, much appreciated!