Warning running "test strfns.cc-tst "

I have noticed:

test /usr/share/octave/7.3.0/etc/tests/libinterp/corefcn/strfns.cc-tst
warning: multi-row character matrix converted to a string, only the first row is used
warning: called from
    __test__ at line 2 column 1
    test at line 683 column 11

warning: multi-row character matrix converted to a string, only the first row is used
warning: called from
    __test__ at line 2 column 1
    test at line 683 column 11
<...more of the same deleted ...>

but the warning did not show up during “make check”.