cond-expand in csm all.options file

The csm build system egg doesn't seem to process cond-expand the options file as described in the documentation, always falling back to the `else` branch. Example all.options:

-program test
(cond-expand
  (release "-O3")
  (else "-O0"))

Passing -D release doesn't change the flag:
$ csm
  '/usr/local/bin/csc' '-o' 'test' '-I' '/tmp/csm' '-C' '-I' '-C' '/tmp/csm' '/tmp/csm/test.sld' '-O0'
$ csm -clean
$ csm -D release
  '/usr/local/bin/csc' '-o' 'test' '-I' '/tmp/csm' '-C' '-I' '-C' '/tmp/csm' '/tmp/csm/test.sld' '-O0'

If an else branch is absent from the cond-expand, csm always signals an error, even when the appropriate feature requirement is passed on the command line.
The bug is present in both CHICKEN 5 and the development 6 version.