Fix referencing virtual table predicates

We need to enumerate first and filter afterward — not the other way
around — because we later use the indexes produced by `enumerate` to
access the original `predicates` slice.

core/translate/main_loop.rs

@@ -457,8 +457,8 @@ pub fn open_loop(
                                 // We then materialise the RHS/LHS into registers before issuing VFilter.
                                 let converted_constraints = predicates
                                     .iter()
-                                    .filter(|p| p.should_eval_at_loop(join_index, join_order))
                                     .enumerate()
+                                    .filter(|(_, p)| p.should_eval_at_loop(join_index, join_order))
                                     .filter_map(|(i, p)| {
                                         // Build ConstraintInfo from the predicates
                                         convert_where_to_vtab_constraint(

testing/cli_tests/extensions.py

@@ -442,6 +442,10 @@ def _test_kv(exec_name, ext_path):
         lambda res: res == "100|updated2",
         "there is only 1 key remaining after setting all keys to same value",
     )
+    limbo.run_test_fn(
+        "select * from t a, other b where b.c = 23 and a.key='100';",
+        lambda res: "100|updated2|23|32|23" == res,
+    )
     limbo.quit()