Make behavior consistent across invocations by pre-sorting incoming files/directories

[jbruchon]

We need to have consistent behavior with identical inputs, both to add proper tests and to make existing tests in other tools (e.g. Debian's deb package consistency tests) behave properly. This is currently causing the Debian tests to fail with v1.19.0 due to reproducibility failures caused by files arriving in a different order across invocations and different primary link targets being chosen as a result. Inputs should be sorted prior to consumption so that they "arrive" in the same order every time.

This should be fixed during my rewrite of the current grokdir() function that will remove recursive function calls.

[eribertomota]

Thanks. It is very important for Debian.

[jbruchon]

I haven't forgotten about this. It's a priority for me coming up. I wasn't developing for a long time but I'm back into it now.

[eribertomota]

Very good. Debian needs this fix. Thanks!