[ToME 1.5.10] Prerequisites apply beyond 5 point talent limi

[BugReporter]

Short description.
After allocating 5 points the talent still must meet level 6 prerequisites for level up window to show that said talent is at its maximum points.
Actual result.
Without meeting requirements for level 6 the 5/5 level talent icon is dark and when you try to click on that icon (with talent points available) the message "Prerequisites not met!" appears.
After meeting requirements for level 6 the 5/5 level talent icon becomes light and clicking on that icon brings "You already fully know this talent!" message.
Expected result.
With or without meeting requirements the icon should either be dark or light for 5/5 talent and only "You already fully know this talent!" message should appear after clicking that icon (when at least 1 point is available).
Steps to reproduce.
I' using berserker and stunning blow as an example here.
1. Get the character to level 5 (without exp penalty killing the Trollmire boss should be enough).
2. Add points to strength to reach 20.
3. Put 5 points into stunning blow.
4. Click on stunning blow. "Prerequisites not met!" appears.
5. Add 2 more points to strength. Stunning blow icon is no longer dark.
6. Click on stunning blow. "You already fully know this talent!" appears.
Game version.
1.5.9 and 1.5.10 for windows from ToME site.
Comment.
This doesn't seem to affect anything, but it was a bit confusing for the first time I noticed this. It may be a deliberate design decision to keep the code simple or for compatibility purpose (like talents where you can put more than 5 points).