#include <windows.h> defines _WIN32. So the subsequent #if defined __mingw32__ || defined _WIN32 || defined _MSC_VER fails for cygwin, leading at every cpan start to cygwin warning: MS-DOS style path detected: /tmp\.UUID_STATE Preferred POSIX equivalent is: /tmp/.UUID_STATE CYGWIN environment variable option "nodosfilewarning" turns off this warning. Consult the user's guide for more details about POSIX paths: http://cygwin.com/cygwin-ug-net/using.html#using-pathnames
There was a long standing bug in the handling of GV <-> CV double linkage that could (and explicitely did with a poisonous perl) cause segfaults at thread destruction. It got fixed by Dave in commit 803f274 which went in 5.13.3, but the fix was amended for 5.13.4 in commit 09aad8f. Since it's not really fair for the user to not be able to install the module because of this, we skip the threads tests for non-author testing unless perl is at least 5.13.4.