parallel_emerge: catch 404 errors when getting packages

parallel_emerge

Index: parallel_emerge
diff --git a/parallel_emerge b/parallel_emerge
index 35c089cdf5fcd0b3c004c7be2e34b25f19462aeb..2d7a97c0eefbe772753537b11566bff608ff5d31 100755
--- a/parallel_emerge
+++ b/parallel_emerge
@@ -813,7 +813,13 @@ class DepGraphGenerator(object):
       url = binhost_url + "/Packages"
 
       prebuilt_pkgs = {}
-      f = urllib2.urlopen(url)
+      try:
+        f = urllib2.urlopen(url)
+      except urllib2.HTTPError as e:
+        if e.code == 404:
+          return {}
+        else:
+          raise
       for line in f:
         if line.startswith("CPV: "):
           pkg = line.replace("CPV: ", "").rstrip()