stream-clone: add the `-exp` prefix to the bundle part We forget to do so in 58adcabc295f, however this is important to prevent "current" client to send incompatible version to future client.

zstd: hack include order to ensure that our zstd.h is found If the regular Python CFLAGS include directories that already have the zstd headers available, a different and possible incompatible version can be picked up otherwise. Sadly, it seems like Python has no easy way to prefix flags before the rest.

exchange: allow passing no includes/excludes to `pull()` I would expect that `exchange.pull(includepats=[])` results in an empty list of include patterns to be passed to the remote, but it doesn't currently because we check for any truthy value instead of checking specifically for `not None`.