Possible solution for reading bundles from stdin

[Aaron Bentley]

Daniel Silverstone wrote:
> I chose to implement a transport (where some might have special-cased in
> bzrlib.bundle.read_bundle_from_url) because I figured it might be of use
> later to have it more generic.

I think it would be much more discoverable to use "-", which is what 
other commands that allow reading from stdin use.  I don't know whether 
that precludes using pipe:///stdin or whether it would just be the 
underlying mechanism.

Aaron