[plt-scheme] Finding R6 libraries with :<n> names

Is this a bug, or am I just missing something obvious?

$ cat run-srfi-foo.sls
#!r6rs
(import (srfi foo))

$ cat run-srfi-800.sls
#!r6rs
(import (srfi :800))

$ cat srfi/foo.sls
#!r6rs
(library (srfi foo) (export) (import))

$ cat srfi/%3A800.sls
#!r6rs
(library (srfi :800) (export) (import))

$ plt-r6rs ++path . run-srfi-foo.sls
$ plt-r6rs ++path . run-srfi-800.sls
run-srfi-800.sls:2:8: import: cannot find suitable installed library at: 
(srfi :800) in: (import (srfi :800))

  === context ===
try-next
/sw/collects/r6rs/private/parse-ref.ss:134:0: parse-import
/sw/collects/scheme/private/map.ss:23:17: loop
/sw/collects/r6rs/main.ss:178:0

Thanks,
David