Ruby: Add another variable capture test

ruby/ql/test/library-tests/dataflow/global/Flow.expected

@@ -1,4 +1,5 @@
 testFailures
+| captured_variables.rb:227:13:227:31 | # $ hasValueFlow=18 | Missing result:hasValueFlow=18 |
 edges
 | blocks.rb:14:12:14:20 | call to source | blocks.rb:8:10:8:14 | yield ... | provenance |  |
 | captured_variables.rb:9:24:9:24 | x | captured_variables.rb:10:10:10:23 | -> { ... } [captured x] | provenance |  |

ruby/ql/test/library-tests/dataflow/global/captured_variables.rb

@@ -214,3 +214,17 @@ class CaptureOverwrite
 
     fn.call()
 end
+
+def multi_capture
+    x = taint(18)
+    y = 123
+
+    fn1 = -> {
+        y = x
+    }
+
+    fn1.call()
+    sink(y) # $ hasValueFlow=18
+end
+
+multi_capture