Add a regression test for #2000

tests/jq.test

@@ -1520,6 +1520,11 @@ import "data" as $e; import "data" as $d; [$d[].this,$e[].that,$d::d[].this,$e::
 null
 "is a test;is too;is a test;is too"
 
+# Regression test for #2000
+import "data" as $a; import "data" as $b; def f: {$a, $b}; f
+null
+{"a":[{"this":"is a test","that":"is too"}],"b":[{"this":"is a test","that":"is too"}]}
+
 include "shadow1"; e
 null
 2