Return success for has_devel()?

[batpigandme]

Possibly an issue for whattheyforgot, but I was confused by silence = success when running devtools::has_devel()for system prep (or perhaps it should be pkgbuild::check_build_tools() based on the usethis vignette here):
https://whattheyforgot.org/set-up-an-r-dev-environment.html#verify-system-prep
https://github.com/jennybc/what-they-forgot/blob/ec7696b21af2110e7f81262fd3cda8fd24c62e32/14_system-prep-for-build.Rmd#L47

Counterarguments:

• It does say:

  If this function runs without error then congratulations, your R installation is properly set up!

• I'm guessing there are good reasons for a successful check to be silent.

Possible alternative

• Create a devel_sitrep() type function (probably in usethis) that is explicitly for returning messages about devel-readiness? (cc @jennybc — I browsed GH issues, but I might have missed something already present)

[batpigandme]

Taken care of here: r-lib/devtools#1970