Fixed io types to make tests work on PY2 once again.py3

Now it's about going through PY3 issues

2 files changed, 6 insertions, 4 deletions

diff --git a/git/index/base.py b/git/index/base.py
index 25ac121c..a994e7b6 100644
--- a/git/index/base.py
+++ b/git/index/base.py
@@ -8,7 +8,7 @@ import os
 import sys
 import subprocess
 import glob
-from io import StringIO
+from io import BytesIO
 
 from stat import S_ISLNK
 
@@ -43,6 +43,7 @@ from git.compat import (
     izip,
     xrange,
     string_types,
+    force_bytes
 )
 
 from git.util import (
@@ -562,7 +563,8 @@ class IndexFile(LazyMixin, diff.Diffable, Serializable):
         st = os.lstat(filepath)     # handles non-symlinks as well
         stream = None
         if S_ISLNK(st.st_mode):
-            stream = StringIO(os.readlink(filepath))
+            # in PY3, readlink is string, but we need bytes. In PY2, it's just OS encoded bytes, we assume UTF-8
+            stream = BytesIO(force_bytes(os.readlink(filepath), encoding='utf-8'))
         else:
             stream = open(filepath, 'rb')
         # END handle stream
diff --git a/git/index/fun.py b/git/index/fun.py
index 004f992e..0e49ae8d 100644
--- a/git/index/fun.py
+++ b/git/index/fun.py
@@ -12,7 +12,7 @@ from stat import (
 
 S_IFGITLINK = S_IFLNK | S_IFDIR     # a submodule
 
-from io import StringIO
+from io import BytesIO
 
 from git.util import IndexFileSHA1Writer
 from git.exc import UnmergedEntriesError
@@ -218,7 +218,7 @@ def write_tree_from_cache(entries, odb, sl, si=0):
     # END for each entry
 
     # finally create the tree
-    sio = StringIO()
+    sio = BytesIO()
     tree_to_stream(tree_items, sio.write)
     sio.seek(0)