xbps-src: do not ignore EEXIST rval from xbps-install(1).
xbps-src: do not ignore EEXIST rval from xbps-install(1).

Due to -I it cannot return EEXIST, and this error value shall
be treated as a real error.

Does not change the current behaviour but will do if we drop -I.

necrophcodr/void-packages,necrophcodr/void-packages,necrophcodr/void-packages,necrophcodr/void-packages,necrophcodr/void-packages