Feeds the digest in a way that makes a unique build identifier.
Obtain the source code. Implementation for local directories will simply return the local source dir, without consideration of the workDir. Implementation of source fetching (archive or scm) will download and extract (or clone) the source tree into workDir.
Add patches to the source code. Patches are patch content, not patch filenames. Patches are applied with Git which must be found in PATH (even if source code is not a Git repo)
Source code interface