Avoid the effects of a revert commit in another Git branch while merging

Question

Working with git flow. We have a co-worker who is not familiar with Git that accidentally merged develop into master yesterday.

Develop has quite a few features tha

Answer 1

Something similar was happening with my team. I actually already have a relatively simple solution, I only found this thread because I was researching ways to prevent this from happening in the first place (still no solution for that).

Here's how I fix it, assuming child branch ("develop") was updated (commit M1) prior to "bad" merge (commit M2) with master:

Problem state

           ... <-- Work after revert that needs merged to develop
            |
            R  <-- Revert Bad Merge
            |
            A  <-- Commits after merge,
            |    /   but before revert 
           ... 

Step 1

# Get latest from both parent and child branches locally

git checkout master
git pull
git checkout develop
git pull


# Merge all code from before revert in master branch to develop
# (not necessary if "bad" merge into master was immediately reverted)

git merge A

State after Step 1:

           ... <-- Work after revert that needs merged to develop
   M3       |
   | \____  R  <-- Revert Bad Merge
   |      \ |
   |        A  <-- Commits after merge,
   |        |    /   but before revert
   |       ... 

Step 2 - IMPORTANT PART!

# Use "ours" strategy to merge revert commit to develop.
# This doesn't change any files in develop. 
# It simplly tells git that we've already accounted for that change.

git merge R -s ours

State after Step 2

   M4
   | \____  ... <-- Work after revert that needs merged to develop
   M3     \ |
   | \____  R  <-- Revert Bad Merge
   |      \ |
   |        A  <-- Commits after merge,
   |        |    /   but before revert
   |       ... 

Step 3

# Merge as normal, from the tip of master to develop.
# This should now be an "easy" merge, with only "real" conflicts.
#  (Those that have changed in both branches)
#
# Note: I've had issues using origin master to merge from latest on remote, 
#   so instead I just ensure I've pulled the latest from master locally and 
#   merge from there

git merge master

State after Step 3

   M5
   | \_____
   M4      \
   | \____  ... <-- Work after revert that needs merged to develop
   M3     \ |
   | \____  R  <-- Revert Bad Merge
   |      \ |
   |        A  <-- Commits after merge,
   |        |    /   but before revert
   |       ... 

Now develop is updated with the latest from master, without having had to resolve repetitive or meaningless merge conflicts. Future merges will behave as normal as well.