dpkg-source: warning: extracting unsigned source package
dpkg-source: warning: extracting unsigned source package (anon-gw-anonymizer-config_5.0-1.dsc)
etc. This does not affect the build. https://forums.whonix.org/t/end-to-end-signed-debs-debsign-debsig-and-dpkg-sig/3446
Can not write log, openpty() failed (/dev/pts not mounted?)
This does not affect the build. This is nothing to be concerned about; it only happens because commands are run inside chroot. Research of this "issue" indicates it is purely cosmetic.
[....] Your system does not have the CPU extensions required to use KVM. Not doing anything. ...[ FAIL ]
This does not affect the build. KVM is installed as a dependency of the build dependency libguestfs-tools. KVM is not needed to build the actual images.
[....] Stopping VirtualBox kernel modules [ ok ].
[....] Starting VirtualBox kernel modules[....] No suitable module for running kernel found ...[ FAIL ]
invoke-rc.d: initscript virtualbox, action "restart" failed.
This does not affect the build. This only means that VirtualBox cannot be started. VirtualBox kernel modules could not be compiled because the {{Code|linux-headers-$(uname -r)}} package was not installed prior to installing VirtualBox (before starting Whonix's build script). The build script doesn't start VirtualBox, hence does not affect the build. The build script only uses {{Code|VBoxManage}} for creation of virtual machine description files and that tool doesn't need VirtualBox kernel modules.
WARNING: The character device /dev/vboxdrv does not exist.
	 Please install the virtualbox-ose-dkms package and the appropriate
	 headers, most likely linux-headers-486.

	 You will not be able to start VMs until this problem is fixed.
This does not affect the build. This is caused by the same issue referenced above.
dpkg: warning: failed to open configuration file '/root/.dpkg.cfg' for reading: Permission denied
This does not affect the build. This happens because {{Code|debuild}} is run as user, not root. It is probably a bug in dpkg. Research of this issue reveals there are many similar bugs in dpkg.
sudo: unable to resolve host host
This does not affect the build. Hostname inside VM image gets changed intentionally to host inside the VM image. The cause probably is package anon-base-files postinst running hostname "$my_host_name" / hostname host. This change should only happen inside the change root chroot. We might get rid of this issue by porting form chroot to systemd-nspawn, but it is not very important. Related forum topic:
[https://forums.whonix.org/t/expected-build-warnings/129 Expected Build Warnings]