https://issues.dlang.org/show_bug.cgi?id=23251

          Issue ID: 23251
           Summary: Deprecation: format specifier "%[a-z]" is invalid
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: ibuclaw@gdcproject.org

Another bogus deprecation message.

Weirdly, `%[a-z]s` is accepted instead, which means the scanf format parser is not treating "%[" as its own specifier.

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