GZipWebClient throws NotImplementedException when used in WP7 background agent

[camradal]

Apparently this check fails

if (_deflatedStream.CanSeek)
    _deflatedStream.Seek(6, SeekOrigin.Current);

Even though the stream claims it supports seek, it actually does not, resulting in NotImplementedException being thrown.

I suspect it has something to do with the different implementation of streams in background agents, since the streams in the main assembly work as expected.

As a workaround, I removed CanSeek check and always do 6 byte reads and it seems to work even for background agents.