Long commit message with multibyte characters is not shown as popup while mouse hovering on the commit in the pull request page

Summary

Long commit message with multibyte characters is not shown as popup while mouse hovering on the commit in the pull request page.

Steps to Reproduce

1. Clone any repo to your local
2. Create a branch "test" from master branch and checkout it

   $ git checkout -b test
   

3. Make any change in the code
4. Commit the change as follows (The commit message is composed of 32 multibyte characters)

   git commit -a -m "ああああああああああああああああああああああああああああああああ"
   

5. Make any change in the code again
6. Commit the change as follows (The commit message is composed of 51 multibyte characters)

   git commit -a -m "あああああああああああああああああああああああああああああああああああああああああああああああああああ"
   

7. Push the changes to new remote branch "test" as follows

   git push origin test:test
   

8. Create a pull request from "test" branch to "master" branch
9. Open the pull request page and select Diff tab
10. Click Show diff of dropdown and mouse hover on the commits you made

Expected Results

Both of the commit messages should be shown while mouse hovering as follows.

Actual Results

The first commit message was not shown while mouse hovering. (The second one was shown.)

Notes

This problem can be reproduced in case that the commit message is composed of 32 ~ 50 multibyte characters.

• If the commit message is longer than 50 multibyte characters, the problem never happens
• If the commit message is in English, the problem never happens

Workaround

There is no workaround at this moment.