SC3009: POSIX.1-2024 now supports brace expansion

[e-kwsm]

https://pubs.opengroup.org/onlinepubs/9799919799/utilities/V3_chap02.html#tag_19_06

When the expansion occurs in a context where field splitting will be performed, a word that contains all of the following somewhere within it, before any expansions are applied, in the order specified:

• an unquoted <left-curly-bracket> ('{') that is not immediately preceded by an unquoted <dollar-sign> ('$')
• one or more unquoted <comma> (',') characters or a sequence that consists of two adjacent <period> ('.') characters surrounded by other characters (which can also be <period> characters)
• an unquoted <right-curly-bracket> ('}')

Note: dash 0.5.12-123-g98cc11a5dbbc does not support the feature yet.