[WIP] trial fix for 9449

[dsyme]

While integrating #6810 into #6811 a regression turned up. This trials the likely fix for it

The problem lies in the fact that an extra constraint is being asserted during optimization. The relevant lines of #6810 are things like this and [this]. The tril fix disables one of these lines during optimization.

However I need to do further analysis for why these lines were needed. Extra constraints should not need to be asserted and it is possile that this call to 'freshen' ultimately meant the other two changes where not needed.

• check if this fix is green
• more analysis needed and trial possible alternative fixes
• add testing around the regression

Note the regression is active even if langversion is not set, which also indicates some inaccurate coding in #6810

[dsyme]

Closing as #9456 is a better fix