I made a mistake in D11562, this port is not compatible with Python 3.
Proposed commit log message:
```
- Limit Python version with 2.7, fails with Python 3:
File "/usr/local/lib/python3.6/site-packages/pyptlib/util/__init__.py", line 56
m = re.match(ur'^\[(.+)\]:(\d*)$', spec)
^
SyntaxError: invalid syntax
Reviewed_by: koobs, cs
Approved by: cs (maintainer), koobs (ports)
Differential_Revision: D13464
```