sort -k doesn't handle locale

[sylvestre]

With bash

$ LC_ALL=fr_FR.UTF-8 locale abmon 2>/dev/null |
        tr ';' '\n'|shuf| nl| LC_ALL=fr_FR.UTF-8 sort -k2,2M
     8	janv.
     5	févr.
    12	mars
     2	avril
    11	mai
    10	juin
     4	juil.
     6	août
     3	sept.
     7	oct.
     9	nov.
     1	déc.

with rut/coreutils:

LC_ALL=fr_FR.UTF-8 locale abmon 2>/dev/null |
        tr ';' '\n'|shuf| nl| LC_ALL=fr_FR.UTF-8 ./target/debug/coreutils sort -k2,2M
     3	avril
     5	févr.
     6	juin
     8	mai
    10	juil.
    11	déc.
    12	août
     1	janv.
     2	mars
     7	sept.
     4	oct.
     9	nov.

Used in gnu tests/misc/sort-month

[ChrisDryden]

Starting looking into this and one of the reasons the test is failing is actually because we have a bug when reading from pipes in sort it appears.

[ChrisDryden]

Actually it was the nl binary that was converting the test non-utf input because of a from_utf8_lossy making a PR for it now

[ChrisDryden]

This was the bug in nl that was also causing that gnu test to fail: #9673

[ChrisDryden]

Created a implementation of a fix using the icu_datetime crate here: #9722