To reproduce:
emacs -Q -f package-initialize --eval "(require 'ob)" --eval "(and (cl-assert
(featurep 'ob)) (cl-assert (not (featurep 'org))))" --eval "(call-interactively
'calendar)"
The emacs needs to be at least 165f738382.
How about, minimally:
diff --git a/lisp/org/org-compat.el b/lisp/org/org-compat.el
index 4446a169d7..ea66bb82be 100644
--- a/lisp/org/org-compat.el
+++ b/lisp/org/org-compat.el
@@ -1043,7 +1043,7 @@ org--setup-calendar-bindings
((guard (not (lookup-key calendar-mode-map "c")))
(local-set-key "c" #'org-calendar-goto-agenda))
(_ nil))
- (unless (eq org-agenda-diary-file 'diary-file)
+ (unless (and (boundp 'org-agenda-diary-file) (eq org-agenda-diary-file 'diary-file))
(local-set-key org-calendar-insert-diary-entry-key
#'org-agenda-diary-entry)))
I suspect other assumptions are made that `ob` cannot be required without `org`.
