[racket-dev] What command should DrDr run by default?

I recently discovered that DrDr runs `raco test` by default on files,
and has since February. However, the DrDr documentation says that it
runs `racket -t`.  I discovered this because the change caused many of
the `net` tests to no longer actually run; see

    http://drdr.racket-lang.org/27042/pkgs/racket-pkgs/racket-test/tests/net/url.rkt

which appears to be successful, even though running `racket` on that
file would have shown the error that I fixed in
https://github.com/plt/racket/commit/a4e529a816 . These tests are a
particularly bad case because they run all their tests in the `main`
submodule, and thus are *not* executed by `raco test`. If the plan is
for everything to run with `raco test`, I'll fix these tests.  But
what is the plan?

Sam