test: improve documentation of some histedit tests
Each test section is clearly separated from the others and gains some
helpful documentation.
test: use a lighter log style in histedit test
The default log displays a log of information that is useless for
histedit tests. Having a cleaner log help readability of those tests a
lot.
This does not change anything to the test semantic.
subrepo: add regression test for
issue3870