on Windows, empty command-line arguments require quotes

[kroening]

Unix-like OSs pass an array of strings to processes as the command line
arguments. Empty arguments do not require special treatment.

By contrast, Windows uses a single string to pass all arguments to the
process. The process parses the string to construct argv[]. To pass an
empty argument, quotes are required.

Note that this is unrelated to any additional parsing a shell might perform.

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