serial.tools.list_ports.comports() does not work

[Hua Yanghao]

The issue is present with both python-serial and python3-serial (ubuntu 15.04), where you got a trace back like below if you want to use list_ports.comports() (or the grep function):
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3/dist-packages/serial/tools/list_ports_posix.py", line 122, in comports
    return [(d, describe(d), hwinfo(d)) for d in devices]
  File "/usr/lib/python3/dist-packages/serial/tools/list_ports_posix.py", line 122, in <listcomp>
    return [(d, describe(d), hwinfo(d)) for d in devices]
  File "/usr/lib/python3/dist-packages/serial/tools/list_ports_posix.py", line 93, in describe
    return usb_lsusb_string(sys_usb)
  File "/usr/lib/python3/dist-packages/serial/tools/list_ports_posix.py", line 80, in usb_lsusb_string
    return base
NameError: name 'base' is not defined

The fix is also very simple (but not sure if this can be a valid fix):
In file: "/usr/lib/python2.7/dist-packages/serial/tools/list_ports_posix.py"
Line: 67, change it to below:
66 def usb_lsusb_string(sysfs_path):
 67 base = os.path.basename(os.path.realpath(sysfs_path))
 68 bus, dev = base.split('-')

So that "base" is properly defined and can be returned.

Attached the version info from apt-show:
hua@grass:~ $ apt-cache show python3-serial
Package: python3-serial
Priority: optional
Section: python
Installed-Size: 281
Maintainer: Ubuntu Developers <email address hidden>
Original-Maintainer: Matthias Klose <email address hidden>
Architecture: all
Source: pyserial
Version: 2.6-1.1ubuntu1
Depends: python3, python3:any (>= 3.3.2-2~)
Suggests: python3-wxgtk3.0 | python3-wxgtk
Filename: pool/main/p/pyserial/python3-serial_2.6-1.1ubuntu1_all.deb
Size: 44348
MD5sum: 749c10727018f02830d2ea704a97e3a9
SHA1: 67dcb133ec940f6ee8a0e9a531adeca2e5d445e3
SHA256: 0f6111b350e901ebafd69945eec47efad4b6dabf1be8e6dc6dab254f72f2d422
Description-en: pyserial - module encapsulating access for the serial port
 This module encapsulates the access for the serial port. It provides
 back-ends for standard Python running on Windows, Linux, BSD (possibly
 any POSIX compliant system). The module named "serial" automatically
 selects the appropriate back-end.
Description-md5: 4dab91c4e71dab549f66bda57e2ecc69
Homepage: http://pyserial.sourceforge.net/
Bugs: https://bugs.launchpad.net/ubuntu/+filebug
Origin: Ubuntu
Supported: 9m
Task: ubuntu-core, cloud-image, ubuntu-core

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Alex (alexthreed)]

Upstream bug: http://sourceforge.net/p/pyserial/patches/26/