Compatibility of backup & DUP_WITNESS

[wubin12]

Wrong backup operation can cause DUP_WITNESS leading to miss block, should solve the compatibility of backup & DUP_WITNESS
#1875

test case
1: DUP_WITNESS function regression test
2: Backup test:
Continuous switching of master and slave node, Not triggering DUP_WITNESS leading to miss block

[Shrey33]

Can you provide some logs and reproduction steps ?

[lvs007]

Can you write how the wrong can come out

[wubin12]