Disable vardb locks globally.

Setting PORTAGE_LOCKS=false could speed up release builders
significantly. We have been running with PORTAGE_LOCKS=false on other
builders for years and we have never encountered any problems with it.
So, set PORTAGE_LOCKS=false on release builders.

BUG=chromium:341175
TEST=Release build.

Change-Id: I5ec838829b5be74d47a59adb5d82f9d8415da863
Reviewed-on: https://chromium-review.googlesource.com/185072
Reviewed-by: Aviv Keshet <akeshet@chromium.org>
Reviewed-by: Matt Tennant <mtennant@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: David James <davidjames@chromium.org>
Tested-by: David James <davidjames@chromium.org>
diff --git a/scripts/parallel_emerge.py b/scripts/parallel_emerge.py
index 25bc53c..4e59572 100644
--- a/scripts/parallel_emerge.py
+++ b/scripts/parallel_emerge.py
@@ -310,10 +310,11 @@
     if "--accept-properties" in opts:
       os.environ["ACCEPT_PROPERTIES"] = opts["--accept-properties"]
 
-    # If we're installing packages to the board, and we're not using the
-    # official flag, we can disable vardb locks. This is safe because we
-    # only run up to one instance of parallel_emerge in parallel.
-    if self.board and os.environ.get("CHROMEOS_OFFICIAL") != "1":
+    # If we're installing packages to the board, we can disable vardb locks.
+    # This is safe because we only run up to one instance of parallel_emerge in
+    # parallel.
+    # TODO(davidjames): Enable this for the host too.
+    if self.board:
       os.environ.setdefault("PORTAGE_LOCKS", "false")
 
     # Now that we've setup the necessary environment variables, we can load the