Fix channel

channels.d/metznet.scm

@@ -1,3 +1,6 @@
+;; See channels.scm for why this needs an explicit import.
+(use-modules (guix channels))
+
 (channel
         (name 'metznet-channel)
         (url "https://git.metznet.ca/MetzNet/metznet-channel"))

channels.d/nonguix.scm

@@ -1,3 +1,6 @@
+;; See channels.scm for why this needs an explicit import.
+(use-modules (guix channels))
+
 (channel
   (name 'nonguix)
   (url "https://gitlab.com/nonguix/nonguix")

channels.d/nonguixgames.scm

@@ -1,3 +1,6 @@
+;; See channels.scm for why this needs an explicit import.
+(use-modules (guix channels))
+
 (channel
         (name 'guix-gaming-games)
         (url "https://gitlab.com/guix-gaming-channels/games.git")

channels.scm

@@ -1,6 +1,14 @@
 ;; channels.scm -- reads the channels.d dir to get a list of channel objects
 
-(use-modules (gnu) ((ice-9 ftw) #:select (scandir)))
+;; guix pull -C pre-imports (guix channels) into the file's environment
+;; (see load-channels/make-user-module in guix/scripts/pull.scm), which is
+;; why this worked without an explicit import. But `guix pull` also
+;; compiles every .scm file under this channel's own checkout as an
+;; ordinary package module (see standard-module-derivation), and that
+;; environment does NOT pre-import it -- so `channel` (a macro from (guix
+;; channels), used in channels.d/*.scm) and %default-channels come up
+;; unbound there unless imported explicitly.
+(use-modules (gnu) (guix channels) ((ice-9 ftw) #:select (scandir)))
 
 (define channel-files
   (scandir "./channels.d"