Empty read from gitdb.OStream.read() before EOF #120

I have code that relies on reading an object from a gitdb stream.

To do this I used with a standard .read() loop (like with io.RawIOBase):

stream = db.stream(bytes.fromhex(sha))
while chunk := stream.read(4096):
    yield chunk

The behaviour I expected to see (from the duck-type with RawIOBase) is to only see b'' at EOF:

If 0 bytes are returned, and size was not 0, this indicates end of file.

However stream.read(4096) can return empty chunks even before the end of the stream, so the loop exits early.

For the file where I saw this first, it is sensitive to the size parameter - it apparently occurs for 0 < size <= 4096.

Looking at the code there is a condition to repeat a read if we got insufficient bytes: