diff --git a/guix-data-service/jobs/load-new-guix-revision.scm b/guix-data-service/jobs/load-new-guix-revision.scm
index 9a81c9c..c4574dd 100644
--- a/guix-data-service/jobs/load-new-guix-revision.scm
+++ b/guix-data-service/jobs/load-new-guix-revision.scm
@@ -469,7 +469,8 @@
   (append supported-system-pairs
           supported-system-cross-build-pairs))
 
-(define (inferior-package-derivations store inf system target start-index count)
+(define* (inferior-package-derivations store inf system target start-index count
+                                       #:key debug?)
   (define proc
     `(lambda (store)
        (define system-target-pair
@@ -539,6 +540,12 @@
                                                     target
                                                     system)
                           (package-derivation store package system))))
+                 (when ,debug?
+                   (simple-format
+                    (current-error-port)
+                    "debug: ~A ~A:~A: ~A\n"
+                    package system target
+                    (derivation-file-name derivation)))
                  ;; You don't always get what you ask for, so check
                  (if (string=? system (derivation-system derivation))
                      (derivation-file-name derivation)
@@ -1522,7 +1529,9 @@ WHERE builder != 'builtin:download'
           (ignore-targets '())
           (extra-inferior-environment-variables '())
           (parallelism 4)
-          inferior-memory-limit)
+          inferior-memory-limit
+          debug?
+          always-compute-derivations?)
   (let ((broken-derivations
          (find-broken-derivations-in-revision
           commit
@@ -1530,7 +1539,8 @@ WHERE builder != 'builtin:download'
           #:ignore-targets ignore-targets)))
     (simple-format #t "~A broken derivations\n"
                    (length broken-derivations))
-    (unless (= 0 broken-derivations)
+    (when (or (not (null? broken-derivations))
+              always-compute-derivations?)
       (run-fibers
        (lambda ()
          (with-exception-handler
@@ -1653,7 +1663,8 @@ WHERE builder != 'builtin:download'
                                          system
                                          target
                                          start-index
-                                         count)))
+                                         count
+                                         #:debug? debug?)))
 
                                    (when last-chunk?
                                      (inferior-cleanup inferior))