cuirass: Clear the build queue when starting.

* src/cuirass/base.scm (clear-build-queue): New procedure.
* bin/cuirass.in (main): Call it.

bin/cuirass.in

@@ -126,6 +126,7 @@ exec ${GUILE:-@GUILE@} --no-auto-compile -e main -s "$0" "$@"
                    (let ((exit-channel (make-channel))
                          (pending
                           (begin
+                            (clear-build-queue db)
                             (log-message "retrieving list of pending builds...")
                             (db-get-builds db '((status pending))))))
 

src/cuirass/base.scm

@@ -49,6 +49,7 @@
             fetch-repository
             compile
             evaluate
+            clear-build-queue
             restart-builds
             build-packages
             prepare-git
@@ -452,6 +453,12 @@ updating DB accordingly."
   (string=? (assq-ref build1 #:derivation)
             (assq-ref build2 #:derivation)))
 
+(define (clear-build-queue db)
+  "Reset the status of builds in DB that are marked as \"started\".  This
+procedure is meant to be called at startup."
+  (log-message "marking stale builds as \"scheduled\"...")
+  (sqlite-exec db "UPDATE Builds SET status = -2 WHERE status = -1;"))
+
 (define (restart-builds db builds)
   "Restart builds whose status in DB is \"pending\" (scheduled or started)."
   (with-store store