Useful Git commands for this are `git commit --patch --amend` and `git rebase --interactive`.
     With a rewritten history you need to force-push the commits:
     ```
     git push --force-with-lease
     ```

   - If there are merge conflicts, you will have to [rebase the branch](https://git-scm.com/book/en/v2/Git-Branching-Rebasing) onto the current **base branch**.
     Sometimes this can be done [on GitHub directly](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/keeping-your-pull-request-in-sync-with-the-base-branch#updating-your-pull-request-branch).
     To rebase locally:
     ```
     git fetch upstream
     git rebase upstream/master
     git push --force-with-lease
     ```

     Use the base branch from step 1 instead of `upstream/master`.

   - If you need to change the base branch, [rebase][rebase].

8. If your PR is merged and [acceptable for releases][release-acceptable], you may [backport][pr-backport] it.

### Pull request template
[pr-template]: #pull-request-template

The pull request template helps to determine which steps have been taken so far.
Details not covered by the title and links to existing related issues should go at the top.

When a PR is created, it will be pre-populated with some checkboxes.

#### Tested using sandboxing

When sandbox builds are enabled, Nix will set up an isolated environment for each build process.
It is used to remove further hidden dependencies set by the build environment, to improve reproducibility.
This includes access to the network during the build outside of `fetch*` functions and files outside the Nix store.
Depending on the operating system, access to other resources is blocked as well; see [sandbox](https://nixos.org/manual/nix/stable/command-ref/conf-file#conf-sandbox) in the Nix manual for details.

Please test builds with sandboxing enabled, because it is also used in [Hydra](https://nixos.org/hydra).

If you are on Linux, sandboxing is enabled by default.
On other platforms, sandboxing is disabled by default due to a small performance hit on each build.

Please enable sandboxing **before** building the package by adding the following to `/etc/nix/nix.conf`:

  ```ini
  sandbox = true
  ```

#### Built on platform(s)

Many Nix packages are designed to run on multiple platforms.
As such, it’s important to let the maintainer know which platforms you have tested on.
It’s not always practical to test all platforms, and it’s not required for a pull request to be merged.
Only check the platforms you tested the build on in this section.

#### Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)

Packages with automated tests are likely merged quicker, because they don’t require as much manual testing.
If there are existing tests for the package, they should be run.
NixOS tests can only be run on linux.
For more details on writing and running tests, see the [section in the NixOS manual](https://nixos.org/nixos/manual/index.html#sec-nixos-tests).

#### Tested compilation of all pkgs that depend on this change using `nixpkgs-review`

If you are modifying a package, you can use `nixpkgs-review` to make sure all packages that depend on the updated package still build.
It can work on uncommitted changes with the `wip` option or on a specific pull request.

Review changes from pull request number 12345:

```ShellSession
nix-shell -p nixpkgs-review --run "nixpkgs-review pr 12345"
```

Alternatively, with flakes (and analogously for the other commands below):

```ShellSession
nix run nixpkgs#nixpkgs-review -- pr 12345
```

Review uncommitted changes:

```ShellSession
nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
```

Review changes from the last commit:

```ShellSession
nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD"
```

#### Tested execution of all binary files (usually in `./result/bin/`)

It's important to test a modified package's executables.