cygwin, #533: Try to make it work with Cygwin's Git.

+ Make `Git.polish_url()` convert paths into Cygwin-friendly paths.
+ Add utility and soe TCs for funcs for detecting cygwin and converting
abs-paths to `/cygdrive/c/...`.
- Cygwin TCs failing:
  - PY2: err: 14, fail: 3
  - PY3: err: 13, fail: 3

1 files changed, 17 insertions, 1 deletions

diff --git a/git/cmd.py b/git/cmd.py
index f0757301..3fc616f5 100644
--- a/git/cmd.py
+++ b/git/cmd.py
@@ -31,6 +31,7 @@ from git.compat import (
 )
 from git.exc import CommandError
 from git.odict import OrderedDict
+from git.util import is_cygwin_git, cygpath
 
 from .exc import (
     GitCommandError,
@@ -191,8 +192,23 @@ class Git(LazyMixin):
     USE_SHELL = False
 
     @classmethod
+    def is_cygwin(cls):
+        return is_cygwin_git(cls.GIT_PYTHON_GIT_EXECUTABLE)
+
+    @classmethod
     def polish_url(cls, url):
-        return url.replace("\\\\", "\\").replace("\\", "/")
+        if cls.is_cygwin():
+            """Remove any backslahes from urls to be written in config files.
+
+            Windows might create config-files containing paths with backslashed,
+            but git stops liking them as it will escape the backslashes.
+            Hence we undo the escaping just to be sure.
+            """
+            url = cygpath(url)
+        else:
+            url = url.replace("\\\\", "\\").replace("\\", "/")
+
+        return url
 
     class AutoInterrupt(object):
         """Kill/Interrupt the stored process instance once this instance goes out of scope. It is