incorrect rendering of spacing combining mark

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• iTerm2 version: 3.2.7
• OS version: 10.14.5 (18F132)
• Attach com.googlecode.iterm2.plist here (drag-drop from finder into this window)

Detailed steps to reproduce the problem:

python3 -c "print('123456'); print('|\u093Fxx|'); print('123456')"

What happened:

The output is

123456
|िxx|
123456

The string on the second line should be 5 characters wide. My browser renders this correctly: The vertical bars are under the 1 and 5. iTerm2 has the vertical bars under the 1 and 4. (Terminal.app is also but differently wrong: It has them under the 1 and 6.)