Fix issue where parallel_emerge complains that packages aren't being installed.

BUG=chromium-os:13697
TEST=Run parallel_emerge -uDNvgp --board=x86-generic chromeos --rebuild

Change-Id: I0bd72b82ae5a64e7fa46a2ddbe04455bc70264c6

R=nsanders@chromium.org

Review URL: http://codereview.chromium.org/6737018
diff --git a/bin/parallel_emerge b/bin/parallel_emerge
index b022ae7..14e38db 100755
--- a/bin/parallel_emerge
+++ b/bin/parallel_emerge
@@ -890,7 +890,8 @@
       # final_pkgs
       for pkg in deps_map:
         for match in final_db.match_pkgs(pkg):
-          final_pkgs.add(str(match.cpv))
+          if match.cpv in deps_info:
+            final_pkgs.add(str(match.cpv))
 
     def FindCycles():
       """Find cycles in the dependency tree.
@@ -1079,20 +1080,6 @@
       if (this_pkg[merge_type] or pkg not in final_pkgs):
         return
 
-      if pkg not in deps_info:
-        emerge_cmd = "emerge"
-        if self.board:
-          emerge_cmd = "emerge-%s" % self.board
-        emerge_cmd += " -pe =%s %s" % (pkg, " ".join(emerge.cmdline_packages))
-        use_str = os.environ.get("USE")
-        if use_str:
-          emerge_cmd = 'USE="%s" %s' % (use_str, emerge_cmd)
-        print "ERROR: emerge has refused to update %s" % pkg
-        print "Are there impossible-to-satisfy constraints in the dependency"
-        print "graph? To debug the issue, try the following command:"
-        print "  %s" % emerge_cmd
-        sys.exit(1)
-
       # Mark this package as non-optional
       deps_info[pkg]["optional"] = False
       this_pkg[merge_type] = True