Residual .repodata directory

[xsuchy]

I deployed createrepo_c on Copr. But after few days, I found that there exist several residual .repodata directory.
I do not have reproducer how this can happen, but this happen.

It would be much better if the createrepo_c would name that directory .repodata-$PID
and just give warning if another .repodata-* directory exist.

This way we user get same information, while on massive scale (as is Copr) flipping critical to warning would allow better continuity of service.

[Tojaj]

I've added a new --ignore-lock option (1b4e120).

If used and a residual .repodata/ exists, than the directory is removed and created again, but it is left empty (to serve as a "lock" which informs other createrepo instances that an instance is running). However, for the temporary data a different temporary directory, with name in format .repodata.datetime.microsec.processpid/, is used instead.

Note: This option is risky and two or more simultaneously running createrepos with the same target directory can lead to the undefined results and corrupted repodata.