Failed to run git-cola if the install prefix contains non-ASCII characters

[Vdragon]

Yeah, another Unicode issue :)
I wonder it's fixable in git-cola...

Reproduce steps

$ make
$ make prefix=build/軟體/git-cola install
$ build/軟體/git-cola/bin/git-cola

Traceback

Traceback (most recent call last):
  File "./bin/git-cola", line 47, in <module>
    setup_environment()
  File "./bin/git-cola", line 39, in setup_environment
    cola_mod = os.path.join(prefix, 'cola', '__init__.py')
  File "/usr/lib/python2.7/posixpath.py", line 83, in join
    path += '/' + b
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe8 in position 98: ordinal not in range(128)

Environment

OS

Ubuntu 14.04LTS x86 64bit

Python

2.7.5 from Ubuntu repo

Locale

zh_TW.UTF-8

[davvid]

Fixed in 8fcc96d