Comment 2 for bug 1571777

10:41 < slangasek> dobey, bdmurray: the concern is whether a
                   hostile ppa could feed the retracers bad symbols
                   that break gdb and compromise the retracer env.
                   I do not assume that gdb has been well-hardened
                   against hostile input
10:43 < dobey> slangasek: right, but i presume we can assume the
               landing silo PPAs to be safe in that regard, since
               we do binary copies from them to archive when landing
10:44 < slangasek> dobey: yes, we can rely on that being safe