Interactive Rebase corrupts 2-bit character commits.

Interactive rebase usually works fine, but when it comes to 2-bit character language such as Korean or Chinese, all 2-bit character will be replaced with "??".
For example, interactive rebase for editing message "English, 한국어, 中國語"(which means English, Korean, Chinese accordingly) actually creates a commit with message of "English, ??????, ??????"