* fixed a problem where the SCM last revision was not getting reset
* change the 400 editing error to just reset the last revision
* handle `source_vars` in the same way as custom scripts
* block unallowed `source_vars` in the validator
* hide POST in OPTIONS for inventory source sublist if not allowed
* Ensure "fresh bits" in dependent jobs
- run IUs in same context and dependent PU
- review docs for update-on-launch expectations
* Avoid customer variable precedence upgrade issues
- only allow SCM types to have overwrite_vars=true
- do not run other cloud sources through the backported script
* Make extra sure to echo stdout and stderr in event of error