Some fixes required for conflicts on revert.

app/models/repository.rb

@@ -628,18 +628,21 @@ class Repository
     target_sha = find_branch(target_branch).try(:target)
 
     # First make revert in temp branch
-    status = target_sha ? true : revert_commit(user, commit, target_branch, base_branch)
+    rm_branch(target_branch) if target_sha
+    success = revert_commit(user, commit, target_branch, base_branch)
 
     # Make the revert happen in the target branch
-    source_sha = find_branch(target_branch).target
-    target_sha = find_branch(base_branch).target
-    has_changes = is_there_something_to_merge?(source_sha, target_sha)
+    if success && !create_mr
+      source_sha = find_branch(target_branch).target
+      target_sha = find_branch(base_branch).target
+      has_changes = is_there_something_to_merge?(source_sha, target_sha)
 
-    if has_changes && !create_mr
-      status = revert_commit(user, commit, base_branch, base_branch)
+      if has_changes
+        success = revert_commit(user, commit, base_branch, base_branch)
+      end
     end
 
-    has_changes && status
+    has_changes && success
   end
 
   def revert_commit(user, commit, target_branch, base_branch)

app/services/commits/revert_service.rb

@@ -14,7 +14,9 @@ module Commits
       if commit
         success
       else
-        error("Something went wrong. Your changes were not committed")
+        error("Sorry, we cannot revert this commit automatically.
+              It may have already been reverted, or a more recent commit may
+              have updated some of its content.")
       end
     rescue Repository::CommitError, Gitlab::Git::Repository::InvalidBlobName, GitHooksService::PreReceiveError, ValidationError => ex
       error(ex.message)
@@ -26,7 +28,7 @@ module Commits
       # Create branch with revert commit
       reverted = repository.revert(current_user, @commit, @target_branch, @create_merge_request)
 
-      unless @create_merge_request
+      if reverted && !@create_merge_request
         repository.rm_branch(current_user, @commit.revert_branch_name)
       end