zenity's text-info mistakes encoding from stdin

Here is the reproducible code for those without /usr/share/dict/ukrainian :
for i in {1..342}; do echo "а" >> test2; done; cat test2 | zenity --text-info; rm test2

And when you reduce the number it detects right encoding:
for i in {1..341}; do echo "а" >> test2; done; cat test2 | zenity --text-info; rm test2

Yes, just what I thought:

$ for i in {1..341}; do echo "а" >> test2; done; wc -c test2; rm test2
1023 test2

$ for i in {1..342}; do echo "а" >> test2; done; wc -c test2; rm test2
1026 test2

It happens when the input exceeds 1024 bytes.

Workaround is to pipe it through
head -c 1023

This bug is an upstream one and it would be quite helpful if somebody experiencing it could send the bug the to the people writing the software. You can learn more about how to do this at https://wiki.ubuntu.com/Bugs/Upstream/GNOME . Thanks in advance!

Thanks, I've reported it and added a watch.