- [x] Have you followed the [guidelines for contributing](https://github.com/snapcore/snapcraft/blob/master/CONTRIBUTING.md)? - [x] Have you signed the [CLA](http://www.ubuntu.com/legal/contributors/)? - [x] Have you successfully run `./runtests.sh static`? - [x] Have you successfully run `./runtests.sh tests/unit`? ----- Currently, when spinning up a remote build, snapcraft calculates a hash of the path for the project being built, and uses that as a unique identifier for the build. This artificially limits the number of builds that can be happening for a given project to 1, which really limits the usefulness of remote builds. Instead of calculating a hash for the project directory, calculate a hash that represents the _state_ of the project, such that changing any file in the working tree (e.g. switching git branches) changes the hash. This allows multiple builds for different versions of a given project to be running at the same time. Of course, this introduces the complication of needing to track such builds. Expose the concept of a "build ID" to the user and allow them to specify it for every remote-build command, so they can check the status of or recover particular builds by providing the relevant build ID.