Fix AttributeError when searching a remote by name

[cesarizu]

Running code like 'origin' in git.Repo('path/to/existing/repository').remotes
raises an AttributeError instead of returning a boolean. This commit fixes that
behaviour by catching the error when doing an identity match on IterableList.

Minimum test case with version 2.1.11:

>>> 'origin' in git.Repo('path/to/existing/repository').remotes
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/cesar/.local/lib/python3.7/site-packages/git/util.py", line 867, in __contains__
    rval = list.__contains__(self, attr)
  File "/home/cesar/.local/lib/python3.7/site-packages/git/remote.py", line 451, in __eq__
    return self.name == other.name
AttributeError: 'str' object has no attribute 'name'

[Byron]

It looks like a single test fails, and I would trust that it is indeed genuine.
Maybe you have some ideas why that would be.
Thanks for your help!

[cesarizu]

I just tried that same test on master and I still see the failure. Also, it doesn't touch the IterableList#__contains__ function (modified in this PR) at all, so it seems unrelated. Or am I missing something here?

[codecov-io]

Codecov Report

Merging #862 into master will increase coverage by 1.06%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #862      +/-   ##
==========================================
+ Coverage    93.6%   94.66%   +1.06%     
==========================================
  Files          59       59              
  Lines        9769     9389     -380     
==========================================
- Hits         9144     8888     -256     
+ Misses        625      501     -124

Impacted Files	Coverage Δ
git/index/util.py	90.69% <0%> (-0.61%)	⬇️
git/index/typ.py	96.82% <0%> (-0.58%)	⬇️
git/objects/tag.py	81.08% <0%> (-0.5%)	⬇️
git/test/test_config.py	98.33% <0%> (-0.47%)	⬇️
git/objects/tree.py	59.64% <0%> (-0.36%)	⬇️
git/objects/base.py	95.83% <0%> (-0.33%)	⬇️
git/refs/tag.py	96.66% <0%> (-0.31%)	⬇️
git/test/test_remote.py	97.54% <0%> (-0.3%)	⬇️
git/refs/reference.py	95.74% <0%> (-0.26%)	⬇️
git/refs/symbolic.py	96.11% <0%> (-0.14%)	⬇️
... and 29 more

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[cesarizu]

In any case, I've just rebased the branch and it's all green now.

[Byron]

Thanks a bunch!