Revert "IPython/utils/tests/test_path.py: Decode UTF-8 paths before passing them to `os.path` functions. Required for running `docker build`s of `jupyter/notebook` containers."

This reverts commit 2ac47388b712e9610c8b3814bb3480193a52e1bb.

IPython/utils/tests/test_path.py

@@ -430,11 +430,11 b' def test_unescape_glob():'
 
 def test_ensure_dir_exists():
     with TemporaryDirectory() as td:
-        d = os.path.join(td, u'∂ir').encode("utf8")
+        d = os.path.join(td, u'∂ir')
         path.ensure_dir_exists(d) # create it
         assert os.path.isdir(d)
         path.ensure_dir_exists(d) # no-op
-        f = os.path.join(td, u'ƒile').encode("utf8")
+        f = os.path.join(td, u'ƒile')
         open(f, 'w').close() # touch
         with nt.assert_raises(IOError):
             path.ensure_dir_exists(f)