SoC-2019-Ideas: add two more ideas

Those are smaller projects, so that Git can accept students from a wider
audience (i.e. students who are not already familiar with C, or with
mailing list-centered project workflows). The downside is that this will
require more effort from the mentors than was common in past years. The
upside is that this will bring all the benefits of more inclusive
development.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

SoC-2019-Ideas.md

@@ -218,6 +218,56 @@ This would consist in taking care of the following issues:
   `This reverts commit <sha-of-rewritten-A>`.)
   Do this for both sha1sums and sha1sum abbreviations in commit messages.
 
+### `git revert --drop` and `git commit --reword`
+
+ - Language: C, shell (bash)
+ - Difficulty: easy
+ - Possible mentors: N/A
+
+The interactive rebase already supports the special oneline prefixes
+`fixup!` and `squash!` in the `--autosquash` mode; these commits will
+be reordered in the todo list and their `pick` commands adjusted
+accordingly.
+
+These commits can be crafted conveniently via the `--fixup` and
+`--squash` options of `git commit`.
+
+The idea of this project is to add two more actions, `drop!` and
+`reword!`:
+
+* The `drop!` action (for convenience, `git revert --drop <commit>`)
+  would not only revert the commit, but a subsequent `git rebase -i
+  --autosquash` would reorder the `drop!` commit directly after the
+  matching commit, then change the matching commit's `pick` to `drop`
+  and comment out the `drop!` one.
+
+* The `reword!` action (for convenience, `git commit --reword <commit>`)
+  would let the user edit the commit message of the referenced commit,
+  and add an "empty" commit (i.e. a commit that does not modify any
+  files) with that commit message, prefixed with the `reword!` oneline.
+  The next `git rebase -i --autosquash` would then not only reorder
+  that commit after verifying that it is indeed an empty commit, it
+  would then also replace the `pick` command with an appropriate new
+  command (say, by extending the `squash` command to accept a `--reword`
+  option).
+
+This project will need to begin by implementing test cases to define
+the expected outcome, and then implement the actual functionality.
+
+### Teach `git stash` to handle unmerged index entries
+
+ - Language: C, shell (bash)
+ - Difficulty: easy
+ - Possible mentors: N/A
+
+When the index is unmerged, `git stash` refuses to do anything. That is
+unnecessary, though, as it could easily craft e.g. an octopus merge
+of the various stages. A subsequent `git stash apply` can detect that
+octopus and re-generate the unmerged index.
+
+See also the discussion in [this Git mailing list
+thread](https://public-inbox.org/git/[email protected]/).
+
 ## Note about refactoring projects versus projects that implement new features
 
 Over the years we have been favoring refactoring projects over