Actually I had to run git bisect one last time (I just became impatient). But the conclusion in my previous email was right.
Saved working directory and index state WIP on (no branch): cfb3c61 Enable dividers in NS (bug#22973)
HEAD is now at cfb3c61 Enable dividers in NS (bug#22973)
0644e6f56d2be82dd716478eb65e7b3c761d813d is the first bad commit
commit 0644e6f56d2be82dd716478eb65e7b3c761d813d
Date: Tue Jun 28 19:03:43 2016 +0300
Fix copying properties in 'format' when it produces padding
* src/textprop.c (extend_property_ranges): Correct range extension
when the new end is beyond the old end. (Bug#23859)
:040000 040000 1e0b14a6241e1817a334ef67fdfef7555c2c8a4b eb7f473f651a351ecbb6edc4bb8c0ab3473edb5b M src