gpg: Print a hint for --batch mode and --delete-secret-key.

* g10/delkey.c: Include shareddefs.h.
(delete_keys): Print a hint.
--

The option --yes has some side-effects so it is not desirable to use it
automatically.  The code in master (2.3) has special treatment of
confirm messages and thus this patch is only for 2.2.

GnuPG-bug-id: 4667
Signed-off-by: Werner Koch <wk@gnupg.org>

g10/delkey.c

@@ -38,6 +38,7 @@
 #include "filter.h"
 #include "../common/ttyio.h"
 #include "../common/i18n.h"
+#include "../common/shareddefs.h"
 #include "call-agent.h"
 
 
@@ -368,6 +369,11 @@ delete_keys (ctrl_t ctrl, strlist_t names, int secret, int allow_both)
         {
           log_error ("%s: delete key failed: %s\n",
                      names->d, gpg_strerror (err));
+          if (gpg_err_code (err) == GPG_ERR_NO_PIN_ENTRY
+              && opt.batch && secret
+              && opt.pinentry_mode == PINENTRY_MODE_LOOPBACK)
+            log_info ("(try option \"--yes\" to delete anyway)\n");
+
           return err;
         }
     }