Move mu-debug to parameters module.

* src/cuirass/mail.scm (mu-debug): Remove it.
* src/cuirass/utils.scm (mu-debug): Ditto.
* src/cuirass/parameters.scm (mu-debug): New variable.
* src/cuirass/remote-server.scm (start-fetch-worker): Force parameters module
load.
* tests/database.scm: Load parameters module.

src/cuirass/mail.scm

@@ -24,9 +24,6 @@
   #:use-module (srfi srfi-19)
   #:export (send-email))
 
-;; This variable is looked up by 'mu-message-send'.
-(define-public mu-debug 0)
-
 ;; Copied from (mumi send-email).
 (define* (compute-message-id message #:optional seed)
   "Return a message ID string."

src/cuirass/parameters.scm

@@ -25,6 +25,9 @@
             %mastodon-instance-url
             %mastodon-instance-token))
 
+;; This variable is looked up by 'mu-message-send'.
+(define-public mu-debug 0)
+
 ;; The URL of the Cuirass web server.  This is useful to send absolute links
 ;; within notifications.
 (define %cuirass-url

src/cuirass/remote-server.scm

@@ -320,6 +320,7 @@ downloading build outputs.  It communicates with the remote server using a ZMQ
 socket."
   (call-with-new-thread
    (lambda ()
+     (use-modules (cuirass parameters)) ;XXX: Needed for mu-debug variable.
      (set-thread-name name)
      (let ((socket (zmq-fetch-worker-socket)))
        (let loop ()

src/cuirass/utils.scm

@@ -57,9 +57,6 @@
 
             date->rfc822-str))
 
-;; This variable is looked up by 'mu-message-send'.
-(define-public mu-debug 0)
-
 (define (alist? obj)
   "Return #t if OBJ is an alist."
   (and (list? obj)

tests/database.scm

@@ -22,6 +22,7 @@
 
 (use-modules (cuirass database)
              (cuirass notification)
+             (cuirass parameters)
              (cuirass remote)
              (cuirass utils)
              ((guix utils) #:select (call-with-temporary-output-file))