fixup! CONTRIBUTING: enhance section about squashing and rebasing

Author: crasbe

CONTRIBUTING.md

@@ -334,66 +334,26 @@ mode, you can find information on rebasing in the
 
 [about-git-rebase]: https://help.github.com/articles/about-git-rebase/
 
-The easiest method is to use the following command that compares the changes
-in your branch to the `master` branch and shows you all the commits you have
-made since in a text editor. You can select, drop, reorder and squash the
-commits here.
+The safest method to squash your commits is to find out the last commit hash
+of the `master` branch with `git log --oneline -n10`. Depending on the number of
+commits you made, `-n` can be bigger or smaller of course.
 
-```console
-$ git rebase master -i
-```
-
-***Note:*** This will automatically rebase your branch to the `master` branch
-afterwards. If a lot of development happened on the `master` branch since you
-have opened your Pull Request, a merge conflict might arise.
+You can then execute `git rebase -i <last master hash>`, which will show you
+all the commits you have made since in a text editor. You can select, drop,
+reorder and squash the commits here.
 
 If you used [fixup commits](#add-fixup-commits-during-review) during the review
 phase, squashing commits can be performed in a single command:
 
 ```console
-$ git rebase -i --autosquash master
-```
-
-If you want to remain on your branch and avoid possible merge conflicts at
-this stage, you can set the starting point relative to the last commit, which
-is called `HEAD` in git terminology:
-
-```console
-$ git rebase -i HEAD~n
-```
-
-You have to replace the `n` with the number of commits you want to go back in
-history.
-You can find out how many commits you made by listing commits with the `log`
-subcommand. For example to show the last 10 commits, you can execute:
-
-```console
-$ git log --oneline -n10
-```
-
-***Watch out:*** Avoid setting `n` higher than the number of your commits as
-this will add commits from the `master` history to your branch and therefore
-create duplicates. If that has happened to you, you can manually run
-`git rebase master`, which will sort out the duplicates again.
-
-If you encounter a merge conflict you could either resolve it by hand with an
-editor and use
-
-```console
-$ git add -p
-```
-
-To add your changes or use a merge tool like [meld](https://meldmerge.org/) to
-resolve your merge conflict.
-
-```console
-$ git mergetool
+$ git rebase -i --autosquash <last master hash>
 ```
 
-Many modern editors and IDEs also feature graphical merge tools that will make
-the merge process a lot easier.
+If you encounter a merge conflict, it is generally easiest to use a merge tool
+like [meld](https://meldmerge.org/) or the built-in merge tool of your editor
+or IDE.
 
-After the merge conflict is resolved you can continue to rebase by using
+After the merge conflict is resolved you can continue the rebase by using
 
 ```console
 $ git rebase --continue