Things took a bit longer than expected, but the RC1 plus all Cygwin modules that I maintain or co-maintain are now available. Please point setup to http://cygwin.stromeko.net/perl-5.26 as an additional installation source and it should let you update. The Perl distributions are release versions that will be offered directly, perl itself is marked as test so you need to mark them for installation in setup for these packages.
After the install you should be able to create test packages with and for the new Perl. If you plan to go back from the test installation, you should probably just have a backup of your Cygwin installation. Regards, Achim. -- +<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+ SD adaptation for Waldorf Blofeld V1.15B11: http://Synth.Stromeko.net/Downloads.html#WaldorfSDada