build: Depend on guile-ssh 0.12.0

This is a followup to 35f35111678e6622301b414f3d464acb71e106bb.

* m4/guix.m4 (GUIX_CHECK_GUILE_SSH): Check for userauth-gssapi!
* doc/guix.texi: Document version requirement

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/m4/guix.m4 b/m4/guix.m4
index 8be7cca54f6..961ce838ac7 100644
--- a/m4/guix.m4
+++ b/m4/guix.m4
@@ -142,13 +142,14 @@ dnl GUIX_CHECK_GUILE_SSH
 dnl
 dnl Check whether a recent-enough Guile-SSH is available.
 AC_DEFUN([GUIX_CHECK_GUILE_SSH], [
-  dnl Check whether 'channel-send-eof' (introduced in 0.10.2) is present.
+  dnl Check whether 'userauth-gssapi!' (introduced in 0.12.0) is present.
   AC_CACHE_CHECK([whether Guile-SSH is available and recent enough],
     [guix_cv_have_recent_guile_ssh],
     [GUILE_CHECK([retval],
       [(and (@ (ssh channel) channel-send-eof)
             (@ (ssh popen) open-remote-pipe)
-            (@ (ssh dist node) node-eval))])
+            (@ (ssh dist node) node-eval)
+            (@ (ssh auth) userauth-gssapi!))])
      if test "$retval" = 0; then
        guix_cv_have_recent_guile_ssh="yes"
      else