Bug fixes and improvements are to be put up for review against each currently supported branch (for example 18) that they are applicable to. Tests (unit tests, Asterisk testsuite tests, or both) should be included if possible to ensure that a regression does not occur in the future.
RegressionsIn Extended And Deprecated Modules
If a bug fix or improvement causes a regression in an extended or deprecated module the project may choose to revert the change in question instead of fixing it at the time of regression. To include the bug fix or improvement again into the tree the regression would need to be fixed by the original contributor, or another individual.