I'm a bit confused, why are you merging things into develop if they're not ready?
If Feature B isn't ready, it should stay in its own branch until it is.
Develop is for code that the developers say is ready. You might have bugs, poor merge resolution, etc, but any fixes made should be quick and should pave the path toward code that can be merged into master. If the problems are major, revert develop.
Master, on the other hand, should always be stable and rock solid. You can then have production servers that always pull master automatically, and staging servers that always pull develop automatically.
I've worked on multiple teams this way it works out quite well.
In the above example, say Feature A gets the go-ahead from the business user/product owner/whatever, and Feature B doesn't. From the dev standpoint both are complete but there may be some business reason to hold up Feature B. The owner(s) of Feature A are likely not going to understand why anything to do with Feature B has to hold up their release.
In your scenario, Feature B should not have been promoted into the development branch until everyone agrees it's going to be shipped. If it got into development without everyone's approval, then that is a business process problem, not a CVS tool problem.
At my last job, we had a 'gorilla' that had to approve every commit, and it was his job to coordinate between the project managers and the developers as to what was allow to be promoted to prevent exactly the scenario you described. It also had the benefit of making developers describe each commit clearly so that the gorilla could understand the change, which made looking at the commit history some time later (months/years) quite a bit easier too.
In that scenario is everything in develop simply waiting to be pushed to master, with no additional testing/approval? At that point why not push directly from feature branches into master?
Because features are not always isolated, sometimes they change behaviour based on changes in other branches. Testing features in isolation is different from testing an entire release.
We follow a similar process where I work and it works really well.
Something being merged into development means that it is 100% complete and ready to be deployed to production at any time. This means all QA and acceptance testing had to happen before merging.
What you're describing doesn't make very much sense. There are only two cases here:
1) A feature that's in develop may sometimes need to wait for something (QA, business validation, a go-ahead, whatever) to go to master, or
2) A feature that's in develop can ALWAYS go to master at any time.
In the first case, you can have feature X blocking all other features because it's in the same branch as them, which is the problem the GP is describing. In the second case, the two branches are the same, so why not just merge into master directly?
It's always #2, but just because a feature has been approved for master, doesn't mean all the features approved for master are stable together.
A feature might be stable as a standalone, but in virtually every software suite, features interact with each other. That is what develop is for. It's where all the feature branches meet and where any instability created by everything coming together is resolved.
Master, on the other hand, is the product of that successful resolution after all the bug fixes.
I've found that that generally leads to problems, so I prefer to have the feature that is going to be merged last be responsible for fitting in with the rest. That way, as described earlier, I don't have to wait for features that can't be merged now to merge the ones that can.
How do you know which feature will be merged last? In the teams I've worked in previously, everything happened in parallel. You had no way of knowing what feature was going to be merged when. So, essentially, we completed a feature-branch, tested it, and merged it into develop. Then, at set intervals, we did some heavy testing on develop and fixed any outstanding bugs, before creating a release by merging to master.
For example:
Team is working on feature A and feature B. Each feature is developed on its own branch.
Feature A is ready for testing/integration, it is merged into develop.
Feature B is ready, it is merged into develop.
Now here is the problem:
Feature B is ready for release, but feature A is not. It is now not possible to merge develop into master without including both features.
The solution I use is to have master and branches. That's it. Master represents currently-running production code. Branches contain everything else.
This also happens to be how Github work. This article explains how it works with various levels of deployment before production - http://githubengineering.com/deploying-branches-to-github-co...