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The fix for PR#14543 caused stack problems with outputing large R objects (e.g. data frames of 25,000 items). (PR#14698)
In a double-byte locale (Chinese, Japanese, Korean), ‘grep()’ and friends might have used byte-wise matching of strings in the native encoding. (PR#14622)
In package ‘parallel’, ‘detectCores(logical = FALSE)’ makes an OS-dependent attempt to find the number of physical cores. It usually succeeds, even on XP.