Make diag() go to stdout: everything else does.
[ccan] / ccan / tap /
drwxr-xr-x   ..
-rw-r--r-- 1366 _info.c
-rw-r--r-- 9751 tap.3
-rw-r--r-- 8834 tap.c
-rw-r--r-- 8187 tap.h
drwxr-xr-x - test