Add a pactest showing failed GPG verification

Signed-off-by: Dan McGee <dan@archlinux.org>

test/pacman/tests/sign002.py

@@ -0,0 +1,10 @@
+self.description = "Verify a signature in a sync DB (failure)"
+
+sp = pmpkg("pkg1")
+sp.pgpsig = "iEYEABECAAYFAkhMOggACgkQXC5GoPU6du2WVQCffVxF8GKXJIY4juJBIw/ljLrQxygAnj2QlvsUd7MdFekLX18+Ov/xzgZ1"
+self.addpkg2db("sync", sp)
+
+self.args = "-S %s" % sp.name
+
+self.addrule("PACMAN_RETCODE=1")
+self.addrule("!PKG_EXIST=pkg1")