Don't add packages to the graph that are left as is due to --upgrade-only.
This is necessary because later code assumes that packages are either from
porttree or bintree whereas the --upgrade-only is almost exclusively from

svn path=/main/branches/2.0/; revision=2199
diff --git a/bin/emerge b/bin/emerge
index 6edc874..1522b57 100755
--- a/bin/emerge
+++ b/bin/emerge
@@ -1317,7 +1317,11 @@
 					except Exception, e:
 						print "Warning: "+str(e)
 					if cand:
-						myeb=cand
+						# --newuse can't work because the installed version isn't available
+						# just pretend like the package doesn't matter
+						# XXX: hidden assumption here that the higher versioned package
+						# satisfies the atom that was given
+						continue
 				if myeb: