how to call gdb_test "" ... ?

[Michael Elizabeth Chastain]

I am reworking gdb.base/list.exp and in the process I'm converting a lot
of send_gdb calls to gdb_test.  (If you want to know why I'm reworking it,
I'm getting rid of the "testcnt" mechanism, which list.exp uses instead
of just issuing a PASS when a test succeeds).

In one place I want to do this:

  gdb_test "list list0.c:10" "..."
  gdb_test "" "..."
  gdb_test "" "..."
  gdb_test "" "..."

That is to say, I want to send a "list" command, and then send some
empty commands and look at the results as usual.

gdb_test does not work with an argument of "".

Is there an easy way to do this, or should I just stick with send_gdb "\n"?
The test script already calls send_gdb "\n" and I don't mind keeping it
that way.  I'm just wondering if someone knows a better idiom.

Michael C