Update parallel_emerge to use no-env-update feature which skips env_update.

parallel_emerge

Index: parallel_emerge
diff --git a/parallel_emerge b/parallel_emerge
index be5b3908ef19a308b7b30a6b5d5f32978be5f2e6..35c089cdf5fcd0b3c004c7be2e34b25f19462aeb 100755
--- a/parallel_emerge
+++ b/parallel_emerge
@@ -327,6 +327,13 @@ class DepGraphGenerator(object):
     # lying around and they cause problems, so for now we disable the flag.
     # TODO(davidjames): Look for a better solution.
     features = os.environ.get("FEATURES", "") + " -collision-protect"
+
+    # If we're cross-compiling, updating the environment every time we install
+    # a package isn't necessary, and leads to race conditions. Do environment
+    # updates at the end, instead.
+    if self.board:
+      features = features + " no-env-update"
+
     os.environ["FEATURES"] = features
 
     # Now that we've setup the necessary environment variables, we can load the
@@ -1315,6 +1322,10 @@ def main():
     if new_world_pkgs:
       world_set.update(new_world_pkgs)
 
+  # Update environment (library cache, symlinks, etc.)
+  if deps.board and "--pretend" not in emerge.opts:
+    portage.env_update()
+
   print "Done"
 
 if __name__ == "__main__":