This blog is updated daily.
A general description is here.
‘R CMD build’ no longer attempts to preserve file permissions on Windows, because Windows (unlike POSIX-complant OSes) stops read-only files being deleted in version-control directories.
‘shell.exec()’ now interprets files relative to the current working directory.
Launching the PDF manuals from the Rgui menus did not work on some versions of Windows.
The sources now work with ‘libpng-1.5.1’, ‘jpegsrc.v8c’ (which are used in the CRAN builds) and ‘tiff-4.0.0beta6’ (CRAN builds use 3.9.1). It is possible that they no longer work with older versions than ‘libpng-1.4.5’.