[Bug] Sometimes the debugger opens with the context one off

Hi,

This one was annoying me for a while: sometimes, when you put a halt the debugger opens but with
exactly the method you put the halt in not selected and hidden (you need to scroll up!).

I analysed a bit the situation and the case were this happens is when you put a halt and then run a test to trigger the halt. Normal halts are ok.


        https://pharo.manuscript.com/f/cases/21236/Sometimes-the-debugger-opens-with-the-context-one-off

fix to review:

        https://github.com/pharo-project/pharo/pull/797