What's wrong with this entry?
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The specific error message directing users from --bg to --pool has been removed along with its logic. The --pool error path is no longer generated.
Evidence
Removed string (search for "--bg and --pool are different backends" — absent from v2.1.174)
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
Related
Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.