BUG/MINOR: sample: Make the `field` converter compatible with `-m found`

Previously an expression like:

    path,field(2,/) -m found

always returned `true`.

Bug exists since the `field` converter exists. That is:
f399b0debfc6c7dc17c6ad503885c911493add56

The fix should be backported to 1.6+.

(cherry picked from commit 4381d26edc03faa46401eb0fe82fd7be84be14fd)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
2 files changed