Update: We ended up using a process very much like this schema (thanks to neuro for the link). We massaged out repository into a state where default is stable (and has the same code as our production environment), we have a dev branch, feature branches for new stuff and use release branches for releases. All seems to be working perfectly.
Our team has recently switched from using SVN (using ToroiseSVN Windows client) to Mercurial (using TortoiseHg Windows client) for version control. We have successfully exported our SVN repository and imported it into a Mercurial repository.
We now have a Mercurial repository where we can see the entire history of revisions (changesets in Mercurial).
Life was simpler in the old days; our development process was not really multi-stream like it is now. The trunk was used to hold all code - even changes that were still in-flight (as long as it didn't break the trunk). When it came to managing releases with SVN, we would checkout the trunk (which holds all code), revert the individual changes we didn't want as part of the release, and create a tag for it.
Cherrypicking the code we want with SVN was easy. Bug-fixing previous releases and ensuring it was part of the trunk was simple too.
In Mercurial, we need to be able to get a snapshot of the "trunk" (default in Mercurial) with individual changes reverted out. We can do this using hg revert.
To snapshot this, we have created a "named branch" - let's call it Build-4.0.1 for now.
Development continues on default as normal when a bug is found in Build-4.0.1. Let's assume the bug is in one of the reverted files. We change the code from the branch for Build-4.0.1, create a new "named branch" (Build-4.0.2) and want to merge it back into default without pushing the reverted code over the top of newer code. How can we accomplish this?
Alternatively, is there a better workflow for managing the releases and our code in Mercurial? I quite like the look of this wonderful SO answer on managing release branches, although I am not sure how we can transition to it from the state we are in now (with in-flight stuff in default).
Note: I have looked at the Transplant extension, but haven't used it yet - could it be part of the solution to this challenge?
Well, to begin with, your use of revert seems strange to me. Usually it is used to revert modifications done to the working copy back to the version of the repository.
The usual way to get the working copy to some point backward is to update :
hg update -r 1234
from there, you can tag, modify, commit, etc.
To merge back you only have to merge your release branch to the default branch. It will work like a charm, unless it is to different/old a release.
Transplant works fine, but do something a bit different from merge : it take your changeset as a "diff" and apply it as a new modification.
To manage your releases, you can look this other answer (by me) :
How to use mercurial for release management?
What we use is a clone / main branch that holds the most stable version, which is released at some points. On this clone : branch, we can fix critical bugs (hotfix). In parallel, we use a dev clone / branch to develop. The hotfixes are merge as soon as completed from stable to dev. When the current development is done, we merge the dev on stable / default.
This schema is pretty good to understand things :)
Good luck !