lwt_eio <= 0.3 tests fail with recent mdx
Due to the extra verbose output
```
\# File "test/test.md", line 1, characters 0-0:
\# /usr/bin/git --no-pager diff --no-index --color=always -u _build/default/test/test.md _build/default/test/.mdx/test.md.corrected
\# diff --git a/_build/default/test/test.md b/_build/default/test/.mdx/test.md.corrected
\# index 1245303..88fb312 100644
\# --- a/_build/default/test/test.md
\# +++ b/_build/default/test/.mdx/test.md.corrected
\# @@ -42,19 +42,19 @@ during each iteration of the main loop, so the Lwt thread runs twice as often.
\# );;
\# +eio: i = 1
\# + lwt: i = 1
\# -+eio: i = 2
\# + lwt: i = 2
\# ++eio: i = 2
\# + lwt: i = 3
\# +eio: i = 3
\# + lwt: i = 4
\# -+ lwt: i = 5
\# +eio: i = 4
\# -+ lwt: i = 6
\# -+ lwt: i = 7
\# ++ lwt: i = 5
\# +eio: i = 5
\# -+ lwt: i = 8
\# ++ lwt: i = 6
\# +eio: i = 6
\# ++ lwt: i = 7
\# +eio: i = 7
\# ++ lwt: i = 8
\# +eio: i = 8
```
Signed-off-by: Marcello Seri <marcello.seri@gmail.com>
anil.recoil.org
mseri.me