Quotes argument lists to be used in Win32 in several different
situations.

Windows passes its arguments as a single string instead of an array as
other platforms do. In almost all cases, the standard Win32
CommandLineToArgvW function is used to parse this string. cmd.exe has
different rules for handling quoting, so extra work has to be done if it
is involved. It isn't possible to consistantly create a single string
that will be handled the same by cmd.exe and the stardard parsing rules.

Perl will try to detect if you need the shell by detecting shell
metacharacters. The routine that checks that uses different quoting
rules from both cmd.exe and the native Win32 parsing. Extra work must
therefore be done to protect against this autodetection.