clear staging repo when builds start

[vobencha]

@gmbecker Currently the staging/ directory is wiped when the builds complete (migrateToFinalRepo()) so those products are not available for troubleshooting. We'd like to instead cleanse staging/ in makeRepo() when the builds start. If you don't see a problem with this I'll submit a pull request.

[gmbecker]

I think this is better as an option than a universal behavior change, but in that context it seems like a good idea.

I'd guess the option would go on the RepoBuildParams object, adn the behavior I'm envisioning is: always clear when starting, clear when finishing unless the option (retainStagingFiles or something, doesn't really matter what its called so long as its intuitively clear) is TRUE, in which case dn't clear during the finishing process.

Does that make sense? Do you see any problems iwth that in regards to your desired usage?

[vobencha]

I think that sounds fine and should work for our use case. I'll put a pull request together and we can go from there.

[vobencha]

@gmbecker ,
I've done a first iteration and have some concerns about adding this option as a new slot in the RepoBuildParam object. A new slot will invalidate existing serialized GRANRepository objects. Even though we don't (yet) have a validity method for the GRANRepository object, using the new getter/setter on an object without the slot will be a problem. We would need an updateObject() function available to the user and called from loadRepo(). Are you ok with this?

Another option would be to add this as a argument to makeRepo(). That may be a little less clean but this action (clear/don't clear staging) does not necessarily need to be recorded in the GRANRepository object. It does not affect reproducibility of the build results so maybe having this be an argument (instead of slot) approach is OK.

[vobencha]

@gmbecker ,
I was talking with @github-rena and she prefers the slot option. I'll go ahead with that option unless I hear back from you.