ENGINE-931: fix for 2.1.27+ issue uncovered in PYADPT-124 (replacement for other cases will come with ENGINE-932)

src/pEpEngine.c

@@ -1158,7 +1158,7 @@ static PEP_STATUS _set_or_update_identity_entry(PEP_SESSION session,
     sqlite3_reset(set_or_update);
     sqlite3_bind_text(set_or_update, 1, identity->address, -1,
             SQLITE_STATIC);
-    sqlite3_bind_text(set_or_update, 2, identity->fpr, -1,
+    sqlite3_bind_text(set_or_update, 2, EMPTYSTR(identity->fpr) ? NULL : identity->fpr, -1,
             SQLITE_STATIC);
     sqlite3_bind_text(set_or_update, 3, identity->user_id, -1,
             SQLITE_STATIC);
@@ -1208,7 +1208,7 @@ static PEP_STATUS _set_or_update_person(PEP_SESSION session,
                 SQLITE_STATIC);
     else
         sqlite3_bind_null(set_or_update, 3);
-    sqlite3_bind_text(set_or_update, 4, identity->fpr, -1,
+    sqlite3_bind_text(set_or_update, 4, EMPTYSTR(identity->fpr) ? NULL : identity->fpr, -1,
                       SQLITE_STATIC);
     int result = sqlite3_step(set_or_update);
     sqlite3_reset(set_or_update);