open func support "utf-8"

[nooperpudd]

Support some Chinese name branches like origin/feature/测试.

[codecov-io]

Codecov Report

Merging #641 into master will decrease coverage by 0.34%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master    #641      +/-   ##
=========================================
- Coverage   92.95%   92.6%   -0.35%     
=========================================
  Files          61      61              
  Lines       10065   10067       +2     
=========================================
- Hits         9356    9323      -33     
- Misses        709     744      +35

Impacted Files	Coverage Δ
git/repo/fun.py	92.59% <100%> (+0.03%)	⬆️
git/refs/symbolic.py	96.45% <100%> (+0.01%)	⬆️
git/compat.py	52.14% <0%> (-11.05%)	⬇️
git/test/test_git.py	97.57% <0%> (-1.22%)	⬇️
git/objects/tree.py	58.47% <0%> (-1.17%)	⬇️
git/test/test_fun.py	97.88% <0%> (-1.06%)	⬇️
git/config.py	91.77% <0%> (-0.99%)	⬇️
git/refs/log.py	93.07% <0%> (-0.77%)	⬇️
git/cmd.py	82.75% <0%> (-0.65%)	⬇️
git/diff.py	98.66% <0%> (-0.45%)	⬇️
... and 2 more

---

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[Byron]

@nooperpudd My apologies for the late reply! Unfortunately I merged plenty of PRs in the wrong order, which is probably the reason yours is conflicting right now. As I would really like to see it merged, maybe you find the time to have another look.
I promise to be fast merging it once the tests on travis pass again.
Thank you so much for your consideration!

[nooperpudd]

@Byron ok, I will fix the problem.

[Byron]

@nooperpudd As always, sorry for getting back to this so late. I have had a look at travis, and besides possibly unrelated failure, one is clearly attributed to codecs working slightly differently in Python > 2.7: https://travis-ci.org/gitpython-developers/GitPython/jobs/293061325#L2480.
Could you have a look again? Thanks a lot.