My last patch changed httprangereader.read to read only the specified
amount of data from the connection, to prevent it from returning more
than what was asked.
I just realized that this could lead to the connection not being closed.
In practice, it looks like the connection is closed just fine, but it's
probably safer to read everything and then return only what's necessary.
revlog.py wasn't trying to detect the version of a revlog file that
doesn't exist on the filesystem (as is the case with old-http).
Additionally, there was an off-by-one error in httprangereader.read
(ranges in HTTP Range headers are inclusive), making it get more data
than what was asked for. This made a struct.unpack complain that
"unpack str size does not match format".
Finally, with the two fixes above, test-static-http fails, since
BaseHTTPServer doesn't understand ranges and returns too much data.
Work around that by reading only the specified amount.
