feat(enc): test with unicode tmpdir

Borrowed from gitpython-developers/GitPython#543

Author: ankostis

.appveyor.yml

@@ -1,6 +1,5 @@
 # CI on Windows via appveyor
 environment:
-
     matrix:
         ## MINGW
         #
@@ -39,6 +38,9 @@ install:
 
     - pip install -e .
 
+    # Test with paths containing the unicode characters.
+    - ln -s /tmp "/tmp/καλημέρα"
+
 build: false
 
 test_script: