Remove most references to hydra.gnu.org.

* Makefile.am (assert-binaries-available): Don't mention hydra.gnu.org
in comment.
* build-aux/check-available-binaries.scm: Likewise.
* build-aux/check-final-inputs-self-contained.scm: Likewise.
* doc/guix.texi (SUBSTITUTE-SERVER): New variable.
Use it throughout instead of "mirror.hydra.gnu.org".
* doc/contributing.texi (Submitting Patches): Likewise.
* gnu/services/base.scm (hydra-key-authorization)
(guix-activation): Remove mentions of "hydra.gnu.org" in comments and
messages.
* gnu/system/install.scm (%installation-services): Likewise.
* guix/scripts/size.scm (guix-size): Likewise.

2 files changed, 3 insertions, 3 deletions

diff --git a/gnu/services/base.scm b/gnu/services/base.scm
index 228d3c5926d..cee9898d79e 100644
--- a/gnu/services/base.scm
+++ b/gnu/services/base.scm
@@ -1518,7 +1518,7 @@ public key, with GUIX."
            (let ((status (cdr (waitpid pid))))
              (unless (zero? status)
                (format (current-error-port) "warning: \
-failed to register hydra.gnu.org public key: ~a~%" status))))))))
+failed to register public key '~a': ~a~%" key status))))))))
 
 (define %default-authorized-guix-keys
   ;; List of authorized substitute keys.
@@ -1630,7 +1630,7 @@ failed to register hydra.gnu.org public key: ~a~%" status))))))))
      ;; otherwise call 'chown' here, but the problem is that on a COW overlayfs,
      ;; chown leads to an entire copy of the tree, which is a bad idea.
 
-     ;; Optionally authorize hydra.gnu.org's key.
+     ;; Optionally authorize substitute server keys.
      (if authorize-key?
          #~(begin
              #$@(map (cut hydra-key-authorization <> guix) keys))
diff --git a/gnu/system/install.scm b/gnu/system/install.scm
index 45b3a0c839f..c345ba0626f 100644
--- a/gnu/system/install.scm
+++ b/gnu/system/install.scm
@@ -250,7 +250,7 @@ You have been warned.  Thanks for being so brave.\x1b[0m
           ;; The usual services.
           (syslog-service)
 
-          ;; The build daemon.  Register the hydra.gnu.org key as trusted.
+          ;; The build daemon.  Register the official server keys as trusted.
           ;; This allows the installation process to use substitutes by
           ;; default.
           (guix-service (guix-configuration (authorize-key? #t)))