When specifying the createdb strategy, the documentation suggests valid
options are FILE_COPY and WAL_LOG, but the code does case-sensitive
comparison and accepts only "file_copy" and "wal_log" as valid.
Fixed by doing a case-insensitive comparison using pg_strcasecmp(), same
as for other string parameters nearby.
While at it, apply fmtId() to a nearby "locale_provider". This already
did the comparison in case-insensitive way, but the value would not be
double-quoted, confusing the parser and the error message.
Backpatch to 15, where the strategy was introduced.
Backpatch-through: 15
Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/90c6913a-1dd2-42b4-8365-ce3b09c39b17@enterprisedb.com
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