lib/pkgdb_conversion.c: avoid copying dangling pointer if "repository-origin" is unexistent.
lib/pkgdb_conversion.c: avoid copying dangling pointer if "repository-origin" is unexistent.

stpx/xbps,datenwolf/xbps,ebfe/xbps,ebfe/xbps,stpx/xbps,ebfe/xbps,stpx/xbps,datenwolf/xbps,datenwolf/xbps