Comment 1 for bug 393309

a much simpler reproduction of the bug is this:

CL-USER> (asdf:load-system :sb-executable)
; Evaluation aborted.
CL-USER> (require :sb-executable)
NIL
CL-USER>

the problem is that *some* contribs have no .asd file. namely these are the offenders:

- sb-executable
- sb-queue
- sb-sprof

(sb-executable doesn't seem to be a tested, generally useful contrib, maybe it should be removed from HEAD?)

some thoughts on asdf integration:

asdf:*central-registry* has the following form:

(LET ((ASDF::HOME (POSIX-GETENV "SBCL_HOME")))
  (WHEN (AND ASDF::HOME (NOT (STRING= ASDF::HOME "")))
    (MERGE-PATHNAMES "site-systems/" (TRUENAME ASDF::HOME))))

but it's pretty useless (also broken), because *system-definition-search-functions* has an entry to look up sbcl contrib .asd's.