How to fix the root of a branch in git?

Question

git

I recently got acquainted with git, but I can’t imagine how I coded without it. So, as it was: I described one feature (3 commits allocated), but then I realized that it would take too much time and put it off, taking on the immediate tasks (sidebar branch). After the layout and basic revival of that siderab, I made a commit and saw that there was a bug that should have been covered (iss_20), but even here the branch for some reason was created from under the iss_18 branch, and not from under the master (although I am 100% sure that created from under it). In general, I need to return the basis of the sidebar and iss_20 branches to the master, because it turns out the wrong picture of development.

Answer 1

git rebase --onto <куда> <начало ветки> <конец ветки>

I don't really understand anything from your picture.
Example from git rebase --help:

First let’s assume your topic is based on branch next.
For example, a feature developed in topic depends on some functionality
which is found in next.

               o---o---o---o---o  master
                    \
                     o---o---o---o---o  next
                                      \
                                       o---o---o  topic

We want to make topic forked from branch master;
for example, because the functionality on which topic depends
was merged into the more stable master branch.
We want our tree to look like this:

               o---o---o---o---o  master
                   |            \
                   |             o'--o'--o'  topic
                    \
                     o---o---o---o---o  next

We can get this using the following command:

           git rebase --onto master next topic

Answer 2

Display bug? The start of the Sidebar branch is not tied to any commit.