Generally we operate in 3 logical source control branches simultaneously, called build, next, and testbed. We determine which branch to apply fixes in based on a number of factors, primarily the urgency of the bug and the anticipated impact of the change.
There's also a live branch where we keep the source for the build currently on live servers. On occasion we apply a server-only fix in the live branch.
Currently build has 1.2, next has 1.1, testbed & live have 1.0.
Soon, probably this weekend, I'll be shuffling the branches, putting 1.1 on testbed, 1.2 on next, and starting the label for 1.3.0.0.
We've had ~47 builds in the 1.1 branch, with additional fixes in each build. QA has been poring over these builds, ensuring the fixes work and don't have unintended consequences. At this point we feel confident that the vast majority of fixes that will go in to 1.1 are in and working.