(use-modules (guix packages)
             (guix git-download)
             (gnu packages web))

(define custom-ikiwiki
  (let ((commit "2b4ab4548c80e608d08602ca4c60cb41e71ff3b2"))
    (package
      (inherit ikiwiki)
      (source (origin
                (method git-fetch)
                (uri (git-reference
                      (url "http://git.cbaines.net/ikiwiki")
                      (commit commit)))
                (sha256
                 (base32
                  "1igbzyy0ys27w73ml7ajcpxy9cxs7v3s9qrcsw4cxb1w7195xi7w"))
                (file-name (string-append "ikiwiki-" (string-take commit 7))))))))

custom-ikiwiki