Published releases origin is ambiguous

[Michael Nelson]

Currently published PPA archives have release files which specify the origin in the format:

LP-PPA-my-lp-name-my-ppa-name

which cannot be used to reliably determine a PPA as the username could be any one of:
 * my,
 * my-lp,
 * my-lp-name,
 * my-lp-name-my,
 * my-lp-name-my-ppa, or even
 * my-lp-name-my-ppa-name (as if the ppa has the default name 'ppa', it is not included in the origin it seems).

It would be great to instead use a reliable delimiter between the username/ppaname.