Per RFC-659, update the deprecation procedure documented in the Developer Guide to (something like; some wordsmithing may be required):

An interface may not be deprecated if doing so would cause other DM-provided code to emit a deprecation warning (of course, this does not apply to end-user code). This means that the ticket which adds the deprecation must also remove all remaining calls to the deprecated interface (updating them to the intended replacement, where appropriate). In some cases, it may be impossible to fully remove the calls to the deprecated code (for example, because it is used to implement some user-facing functionality which is also being deprecated); in this eventuality, the lsst.utils.deprecated.suppress_deprecations decorator may be used to temporarily suppress the warning.