o If a long option looks like an ambiguous abbreviation of two or more long
options, but all the possible interpretations would return the same
value, then just return that value without complaining that it's
ambiguous.
o If a long option could be interpreted either as an exact match for one
long option, or as an abbreviation for one or more other long options,
then treat it as the exact match.
These changes align NetBSD's getopt_long(3) with the current behavior of
GNU getopt_long(3), the de facto standard, and FreeBSD's getopt_long(3).
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