`offset` argument of the `clang-format` utility expects bytes, but code-points are passed

Clang-format utility expects bytes as `offset` argument. But seems like Qt-creator passed code-points instead of them.

Affected commands:

• ClangFormat->FormatAtCursor
• TextEditor->AutoIndentSelection (because, since version 4.8.0, Qt Creator starts using clang-format based indentation)

Does not affected commands:

• ClangFormat->FormatFile (because respective clang-format call doesn't have offset argument)

UPDATE:
the problem still appears. Snapshot: qtcreator-4.8.0-beta2_2595 (revision e6eb0bc032)

UPDATE 2:

actions to reproduce this issue has been added in the comments below