merge of merge brings changes in twice which causes problems when builds pass

Steps:

 * create change 1

 * create merge change on top of the previous change

 * stage change 1

 * stage merge change

 * => merge of merge is created =>change 1 is included twice in the build ref

 ( http://10.212.3.36/coin/integration/qt/tqtc-qt5/tasks/1574588791 )

 * => when build succeeds, change are left in "integrating status"

gerrit log:

[2019-11-24 09:51:15,555] [SSH gerrit-plugin-qt-workflow staging-approve --project qt/tqtc-qt5 --branch tqtc/vxworks-5.9 --build-id refs/builds/qtci/tqtc/vxworks-5.9/1574588791 --result pass --message (qt_ci_bot)] INFO com.googlesource.gerrit.plugins.qtcodereview.QtCommandBuildApprove : qtcodereview: staging-approve -p qt/tqtc-qt5 -i refs/builds/qtci/tqtc/vxworks-5.9/1574588791 -r pass -m - -b tq
tc/vxworks-5.9

[2019-11-24 09:51:15,654] [SSH gerrit-plugin-qt-workflow staging-approve --project qt/tqtc-qt5 --branch tqtc/vxworks-5.9 --build-id refs/builds/qtci/tqtc/vxworks-5.9/1574588791 --result pass --message (qt_ci_bot)] INFO com.googlesource.gerrit.plugins.qtcodereview.QtUtil : qtcodereview: merge fast forward commit 5418c8a4f2288247538d7fe17f3b3a8993ae25f4 1574588681 t-sp on top of commit 4fabcfd5d1
26844b6beea9336350a0a1de6e9e77 1523387629 -tr-sp

[2019-11-24 09:51:15,655] [SSH gerrit-plugin-qt-workflow staging-approve --project qt/tqtc-qt5 --branch tqtc/vxworks-5.9 --build-id refs/builds/qtci/tqtc/vxworks-5.9/1574588791 --result pass --message (qt_ci_bot)] INFO com.googlesource.gerrit.plugins.qtcodereview.QtUtil : qtcodereview: merge commit for AnyObjectId[5418c8a4f2288247538d7fe17f3b3a8993ae25f4] added to qt/tqtc-qt5,refs/heads/tqtc/vxwo
rks-5.9
[2019-11-24 09:51:15,661] [SSH gerrit-plugin-qt-workflow staging-approve --project qt/tqtc-qt5 --branch tqtc/vxworks-5.9 --build-id refs/builds/qtci/tqtc/vxworks-5.9/1574588791 --result pass --message (qt_ci_bot)] ERROR com.googlesource.gerrit.plugins.qtcodereview.QtCommandBuildApprove : qtcodereview: staging-napprove failed to update change status com.google.gerrit.server.update.UpdateException: java.lang.IllegalArgumentException: cannot chain ref update CREATE: 0000000000000000000000000000000000000000 8bcb9ce1b0e56de7b51885c9679cb1eb104c2f48 refs/changes/53/282353/4 after update CREATE: 0000000000000000000000000000000000000000 4b2d02adfb5fcb0bc100fb224455502349a1ad19 refs/changes/53/282353/4 with different new ID