Expect tests include bad path information

[yminsky]

I"m not sure how to deal with this. Here's an example of a problematic section:

  $ dune runtest
       patdiff (internal) (exit 1)
  (cd _build/default && /home/yminsky/Documents/code/rwo/_build/install/default/bin/patdiff -keep-whitespace -location-style omake -ascii test.ml test.ml.corrected)
  ------ test.ml
  ++++++ test.ml.corrected
  File "test.ml", line 32, characters 0-1:
   |    "%4.2f: %s\n"
   |    offset
   |    (match result with
   |    | `Consumed -> "C"
   |    | `No_capacity -> "N")
   |
   |
   |[@@@part "2"];;
   |
   |let%expect_test _ =
   |  let lim = limiter () in
   |  let consume offset = consume lim offset in
   |  (* Exhaust the rate limit, without advancing the clock. *)
   |  for _ = 1 to 3 do
   |    consume 0.
   |  done;
  -|  [%expect {| |}];
  +|  [%expect {|
  +|    0.00: C
  +|    0.00: C
  +|    0.00: C |}];
   |  (* Wait until a half-second has elapsed, try again *)
   |  consume 0.5;
  -|  [%expect {| |}];
  +|  [%expect {| 0.50: C |}];
   |  (* Wait until a full second has elapsed, try again *)
   |  consume 1.;
  -|  [%expect {|  |}]
  +|  [%expect {| 1.00: C |}]
  [1]

Note the /home/yminsky/documents. Here's the PR that shows this behavior:

#3447