1) create a new document with blank template
2) Type paragraph A
3)Type paragraph B
4) Set a on style "Head"
5) Edit the "Head" paragraph style (switch to italic) (not the A paragraph)
6) Set B paragraph to Head
B is italic but A remains in the original style.
A has not been updated when changing the style of "Head"
I cannot confirm this particular bug. The particular case you outlined above worked for me when I tried your approach. But there is something fishy going on there because I saw other strange things. The maintainer should definitely look at it so I'm confirming the bug in general even if that particular behaviour was not observed.
Btw, which version is this? 2.4.0 or 2.5.0alpha?
what strange things do you observe? maybe I can reproduce it
*** This bug has been marked as a duplicate of bug 283351 ***
*** This bug has been marked as a duplicate of bug 296487 ***