Added test cases for return in except statements.

tests/exception/tnestedreturn2.nim

@@ -0,0 +1,20 @@
+discard """
+  file: "tnestedreturn.nim"
+  outputsub: "Error: unhandled exception: Problem [EOS]"
+  exitcode: "1"
+"""
+
+proc test4() =
+  try:
+    try:
+      raise newException(EOS, "Problem")
+    except EOS:
+      return
+  finally:
+    discard
+
+# Should cause unhandled exception error,
+# but could cause segmentation fault if 
+# exceptions are not handled properly.
+test4()
+raise newException(EOS, "Problem")