cli: let the user know which protocol is unknown or unsupported

The current error message is not helpful.

diff --git a/crypto.c b/crypto.c
index da0289dcf392db8b9277d0a9fa5dbca9bd3a2f86..feae9494714edebbe77a7c650bf33b50789de97b 100644 (file)
--- a/crypto.c
+++ b/crypto.c
@@ -81,7 +81,8 @@ notmuch_crypto_get_context (notmuch_crypto_t *crypto, const char *protocol)
            return protocols[i].get_context (crypto);
     }
 
-    fprintf (stderr, "Unknown or unsupported cryptographic protocol.\n");
+    fprintf (stderr, "Unknown or unsupported cryptographic protocol %s.\n",
+            protocol);
 
     return NULL;
 }