lp-shell disables importing of Python modules from '.'

[Dan Watkins]

By the looks of it, the empty string is removed from PYTHONPATH/sys.path, meaning the current directory isn't searched. (I reproduced with both ipython and python for lp-shell, but went with consistent output for comparison here.)

$ ls
livefs_build.py

$ python
Python 2.7.10 (default, Oct 14 2015, 16:09:02)
[GCC 5.2.1 20151010] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import livefs_build
>>> import sys
>>> sys.path
['', '/usr/lib/python2.7', '/usr/lib/python2.7/plat-x86_64-linux-gnu', '/usr/lib/python2.7/lib-tk', '/usr/lib/python2.7/lib-old', '/usr/lib/python2.7/lib-dynload', '/usr/local/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages/PILcompat', '/usr/lib/python2.7/dist-packages/gtk-2.0', '/usr/lib/pymodules/python2.7', '/usr/lib/python2.7/dist-packages/ubuntu-sso-client']

$ lp-shell production devel --python
Connected to LP service "https://api.launchpad.net/" with API version "devel":
Note: LP can be accessed through the "lp" object.
>>> import livefs_build
Traceback (most recent call last):
  File "<console>", line 1, in <module>
ImportError: No module named livefs_build
>>> import sys
>>> sys.path
['/usr/bin', '/usr/lib/python2.7', '/usr/lib/python2.7/plat-x86_64-linux-gnu', '/usr/lib/python2.7/lib-tk', '/usr/lib/python2.7/lib-old', '/usr/lib/python2.7/lib-dynload', '/usr/local/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages/PILcompat', '/usr/lib/python2.7/dist-packages/gtk-2.0', '/usr/lib/pymodules/python2.7', '/usr/lib/python2.7/dist-packages/ubuntu-sso-client']

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: lptools 0.2.0-2
ProcVersionSignature: Ubuntu 4.2.0-16.19-generic 4.2.3
Uname: Linux 4.2.0-16-generic x86_64
ApportVersion: 2.19.1-0ubuntu5
Architecture: amd64
Date: Thu Dec 10 12:21:18 2015
EcryptfsInUse: Yes
InstallationDate: Installed on 2014-09-04 (462 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
PackageArchitecture: all
SourcePackage: lptools
UpgradeStatus: Upgraded to wily on 2015-10-21 (49 days ago)