Start up compat and encoding files

There were a few things which were being reused consistently for
compatibility purposes, such as the `buffer`/`memoryview` functions
as well as the `izip` method which needed to be aliased for
Python 3.  The `buffer` function was taken from `smmap` [1] and
reworked slightly to handle the optional third parameter.

This also adds a compatibility file dedicated entirely to encoding
issues, which seem to be the biggest problem.  The main functions
were taken in part from the Django project [2] and rewritten
slightly because our needs are a bit more narrow.

A constants file has been added to consistently handle the
constants which are required for the gitdb project in the core
and the tests.  This is part of a greater plan to reorganize
the `util.py` file included in this project.

This points the async extension back at the original repository
and points it to the latest commit.

[1]: https://github.com/Byron/smmap/blob/1af4b42a2354acbb53c7956d647655922658fd80/smmap/util.py#L20-L26
[2]: https://github.com/django/django/blob/b8d255071ead897cf68120cd2fae7c91326ca2cc/django/utils/encoding.py

1 files changed, 3 insertions, 5 deletions

diff --git a/gitdb/test/db/lib.py b/gitdb/test/db/lib.py
index a6cdbbe..d0028b8 100644
--- a/gitdb/test/db/lib.py
+++ b/gitdb/test/db/lib.py
@@ -35,7 +35,7 @@ class TestDBBase(TestBase):
     """Base class providing testing routines on databases"""
 
     # data
-    two_lines = "1234\nhello world".encode("ascii")
+    two_lines = "1234\nhello world"
     all_data = (two_lines, )
 
     def _assert_object_writing_simple(self, db):
@@ -81,8 +81,7 @@ class TestDBBase(TestBase):
 
                 prev_ostream = db.set_ostream(ostream)
                 assert type(prev_ostream) in ostreams or prev_ostream in ostreams
-
-                istream = IStream(str_blob_type, len(data), BytesIO(data))
+                istream = IStream(str_blob_type, len(data), BytesIO(data.encode("ascii")))
 
                 # store returns same istream instance, with new sha set
                 my_istream = db.store(istream)
@@ -131,8 +130,7 @@ class TestDBBase(TestBase):
         """Test generic object writing using asynchronous access"""
         ni = 5000
         def istream_generator(offset=0, ni=ni):
-            for data_src in xrange(ni):
-                print(type(data_src), type(offset))
+            for data_src in range(ni):
                 data = bytes(data_src + offset)
                 yield IStream(str_blob_type, len(data), BytesIO(data))
             # END for each item