fix(hypothesis): clear up error message when expect fails

[mattiascockburn]

If the expect string includes strings that should be replaced the debug/error message should include the final expect string where all placeholders are substituted. Otherwise the user is lead to believe that the substitution itself failed.

[mattiascockburn]

@Lawouach do you think this is a good idea or should i rework this?

[Lawouach]

@mattiascockburn I think it makes a lot of sense

[Lawouach]

It seems that breaks at least one test. That's good :)

[mattiascockburn]

@Lawouach hopefully i fixed it up enough :-)

[Lawouach]

Hey @mattiascockburn sorry for being a tad slow on this one. I cannot see the changelog entry in any of the commits though.

[mattiascockburn]

@Lawouach sorry i was just being stupid and forgot to add my changes to the commit :-/