TortoiseGitMerge undo / redo can cause window to become unresponsive

What steps will reproduce the problem?

1. Create a new local Git repository
2. Commit a file test.txt with content test (commit message does not matter)
3. Change the content of test.txt to test1
4. Open the Git Commit dialog
5. Double click the modified test.txt file
6. Select "Double pane view"
7. In the "Working Tree" pane change the content back to test
   ℹ The file name has now a * indicating a change
8. Click the "Save file" icon
9. Click "Undo"
10. Click "Redo"
    ❌ The window freezes

What is the expected output? What do you see instead?

Actual: The window becomes unresponsive

What version of TortoiseGit and Git are you using? On what operating system?

TortoiseGitMerge 2.13.0.0 - 64 Bit, Jan 31 2022
libsvn_diff 1.8.0, -dev
apr 1.6.5
apr-util 1.6.1

Microsoft Windows [Version 10.0.19043.1706]

Please provide any additional information below.

Possibly related to #3781 (closed)