Yeah, AppVeyor is having trouble to connect to GitHub right now, I restarted the build 4 times before getting it finished, and I faced similar issues at different times like that:

Cloning into 'C:/projects/daemon/libs/pdcursesmod'...
Cloning into 'C:/projects/daemon/libs/breakpad'...
fatal: unable to access 'https://github.com/DaemonEngine/breakpad.git/': TLS connect error: error:00000000:lib(0)::reason(0)
fatal: clone of 'https://github.com/DaemonEngine/breakpad.git' into submodule path 'C:/projects/daemon/libs/breakpad' failed

git clone -q https://github.com/DaemonEngine/Daemon.git C:\projects\daemon
fatal: unable to access 'https://github.com/DaemonEngine/Daemon.git/': TLS connect error: error:00000000:lib(0)::reason(0)