This page is mostly directed to core developers with commit access to upstream repositories.
For instructions on basic usage, see Git.
For determining who is allowed to do what, see Organisation.
For guidelines about overall pull request quality, see Merging core pull requests to upstream.
Upstream branch rules
Feature freezes take effect in the master branch, and while the freeze is active, a separate development branch ("dev", or some other suitable name) is made into which pull requests are merged. It is then rebased onto master once the freeze is over. (It can be extended to be a more complete release model later, but this is the important part for now.) (https://forum.minetest.net/viewtopic.php?f=3&t=11172)
Note that 0.4.12 was freezed differently and the freeze will not be made in the same way in the future.
The minetest and minetest_game contain the stable-0.4 branch, which has to be updated to the latest stable 0.4 series version at each release.
Upstream pull requests and issues
- Don't mix multiple things in one commit. The same applies to codestyle cleanup.
- If a pull request or an issue does not get a response from its author in one month (when requiring more details), it is closed.
- If an issue is a duplicate, refer to the first one and close the later ones.
- People considering merging pull requests are not required to look anything up anywhere else than the pull request and its comments. If there is something blocking the merging of a pull request, the reason must be added as a comment to the pull request. This goes both ways: If you check a pull request to be mergeable, write a simple "+1" comment to it.
Upstream commit rules
- You can push something to upstream only if two members of the core team agree on it. (See Organisation.)
- Commit messages must start with a capital letter and be in the present tense (look at the commit log)
- Do not modify history older than 10 minutes
- Use rebase, not merge, to get linear history. 
- Do not rush with anything, unless our users' data is about to be corrupted otherwise
Rule 1 in practice
Tell people openly what you do, and if someone finds a problem in what you do, allow resolving to take its time.
If you have a small patch, fixing some compiler error or other trivial mistake, notify about fixing it on #minetest-dev, wait for 5...15 minutes and push it. To save time, you should notify when finding the problem, not when having it fixed. If someone asks something about it, delay pushing and link the patch  or tell whatever else people want to know.
 Upstream is at https://github.com/minetest
 The team: https://github.com/minetest?tab=members
 For a GitHub pull request, this is easiest done by appending .patch to the pull request URL, wgetting it to your project directory and doing
git am whatever.patch. Similarly for single commits.
 Patches can be linked using a pastebin or by using GitHub (pull request or not).