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The internal ‘untar()’ (as used by default by ‘R CMD INSTALL’) now knows about some ‘pax’ headers which ‘bsdtar’ incorrectly includes in ‘tar’ files, and will skip them with a warning.
R configured with ‘--disable-openmp’ would mistakenly set ‘HAVE_OPENMP’ (internal) and ‘SUPPORT_OPENMP’ (in ‘Rconfig.h’) even though no OpenMP flags were populated.