pass rocksdb oncall to mysql_mtr_filter otherwise tasks get created w…

Summary:
…rong owner

 mysql_mtr_filter script needs proper oncall
Closes https://github.com/facebook/rocksdb/pull/1586

Differential Revision: D4245150

Pulled By: anirbanr-fb

fbshipit-source-id: fd8577c

build_tools/rocksdb-lego-determinator

@@ -100,7 +100,7 @@ CONTRUN_NAME="ROCKSDB_CONTRUN_NAME"
 # the value of $ONCALL. If it's a diff then just call `false` to make sure
 # that errors will be properly propagated to the caller.
 if [ ! -z $ONCALL ]; then
-  TASK_CREATION_TOOL="/usr/local/bin/mysql_mtr_filter --rocksdb"
+  TASK_CREATION_TOOL="/usr/local/bin/mysql_mtr_filter --rocksdb --oncall $ONCALL"
 else
   TASK_CREATION_TOOL="false"
 fi