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Approximately a week before release, the trunk should be frozen for code updates. Announce this The code will be frozen after the last committer meeting prior to the start of the test phase in order to give committers the opportunity to object to the imminent code freeze due to important outstanding changes.
Once the group consensus is reached, announce the code freeze to the dev mailing list.
At this stage, the only updates that may occur in trunk are non-code related or any problem discovered during testing that is considered a show-stopper. As release manager, you will need to make judgements on a case-by-case basis on what kind of problem constitutes a show-stopper for the release, and whether the release date should be pushed to allow for additional testing.
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