Rationale for this patch: It can be used to reduce the number of files
pulled into the build when used as in the #:select? part of the source
clause.

Example:

(define-public example
  (package
    (name "example")
    ; …
    (source (local-file %source-dir
      #:recursive? #t
      #:select? hg-predicate))
    ; …
    ))

Best wishes,
Arne
-- 
Unpolitisch sein
heißt politisch sein
ohne es zu merken