Merge branch 'tc-move-t-minus-zero' into 'master'

Move T-0 to "Prevent updates to the primary"

Closes #743

See merge request gitlab-com/migration!186
2 jobs for master in 17 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Test
passed #2714250
references

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passed #2714249
shellcheck

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