* Fix parser expanding dots where it shouldn't
Previously, the parser would expand "a...b" as "a../..b". Now, >2 dots
are only expanded when the whole path component consists of dots (i.e.,
"..." expands to "../.." while "a...b" stays as it is).
* Respect OS separator when expanding >2 dots
"..." now expands to either "../.." or "..\..", based on the host OS.
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