ONOS-4344 Fixes to onos_stage.py to fix Buck onos-package

Change-Id: I807a3cf66f15c60adb5790bdb54d4b68ea7f953d
diff --git a/tools/package/BUCK b/tools/package/BUCK
index 19c7db1..27c0274 100644
--- a/tools/package/BUCK
+++ b/tools/package/BUCK
@@ -99,7 +99,7 @@
 
 genrule(
   name = 'onos-package',
-  out = 'onos.zip',
+  out = 'onos.tar.gz',
   bash = 'cp $(location :onos-karaf) $OUT && $(exe //buck-tools:onos-stage) $OUT ' + ' '.join(sources),
   visibility = [ 'PUBLIC' ],
 )
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