app-arch/tar-1.29 has apparently acquired some new command line order dependencies that previous version did not have. flexbackup-1.2.1-r12 erroneously includes some files in the tarball multiple times when used with the new tar. The attached patch reorders a command line option to avoid the bug and the attached modified ebuild applies the patch. This change has proven to be backward compatible with all earlier versions of tar that are still in the tree. This bug was initially discussed on the Forums here: https://forums.gentoo.org/viewtopic-t-1054416.html and the credit for the fix should go to Forum user Princess Nell.
Created attachment 454828 [details, diff] Patch to correct the issue.
Created attachment 454830 [details] Modified ebuild applies the above patch.
Why no unified diff of the changed ebuild instead?
Well, I've been chastised for just including the diff in the past. If that's standard practice, I'll do so going forward.
Created attachment 454862 [details, diff] Patch to ebuild to apply the above patch.
flexbackup-1.2.1-r13 includes this patch.
Resolving as the patch is now in the Portage tree.