Autodetect Expect: 100-continue support

[GoogleCodeExporter]

There seem to be some swift servers that do not properly handle 100-continue. 
It would be nice to autodetect this and work around the issue if necessary.

We should still log a big warning though, as this can seriously hurt 
performance in some situations.

For the autodetection, we probably have to send a (small) body right away 
without waiting, and then test if the response starts with 100 (supported) or 
417 (unsupported).. but maybe there are even more broken servers that will 
reply 2xx instead?

Original issue reported on code.google.com by Nikolaus@rath.org on 13 Dec 2013 at 4:36

[GoogleCodeExporter]

Moved to 
https://bitbucket.org/nikratio/s3ql/issue/7/autodetect-expect-100-continue-suppo
rt

Original comment by Nikolaus@rath.org on 28 Dec 2013 at 2:20

• Changed state: Moved