Confirming the bug here, I have the following on my machine:
W: gpgv:/var/lib/apt/lists/ppa.launchpad.net_git-core_ppa_ubuntu_dists_xenial_InRelease: The repository is insufficiently signed by key E1DD270288B4E6030699E45FA1715D88E1DF1F24 (weak digest)
W: gpgv:/var/lib/apt/lists/ppa.launchpad.net_gnome3-team_gnome3_ubuntu_dists_xenial_InRelease: The repository is insufficiently signed by key 9D542E3D52C801D9F8E31682F1773AF13B1510FD (weak digest)
W: gpgv:/var/lib/apt/lists/ppa.launchpad.net_noobslab_themes_ubuntu_dists_xenial_InRelease: The repository is insufficiently signed by key 4FA44A478284A18C1BA4A9CAD530E028F59EAE4D (weak digest)
W: gpgv:/var/lib/apt/lists/dl.google.com_linux_chrome_deb_dists_stable_Release.gpg: The repository is insufficiently signed by key 4CCA1EAF950CEE4AB83976DCA040830F7FAC5991 (weak digest)
W: gpgv:/var/lib/apt/lists/ppa.launchpad.net_numix_ppa_ubuntu_dists_xenial_InRelease: The repository is insufficiently signed by key 43E076121739DEE5FB96BBED52B709720F164EEB (weak digest)
W: gpgv:/var/lib/apt/lists/dl.google.com_linux_earth_deb_dists_stable_Release.gpg: The repository is insufficiently signed by key 4CCA1EAF950CEE4AB83976DCA040830F7FAC5991 (weak digest)
W: gpgv:/var/lib/apt/lists/ppa.launchpad.net_otto-kesselgulasch_gimp-edge_ubuntu_dists_xenial_InRelease: The repository is insufficiently signed by key FB97E9C3A97F85C095AEA7903BDAAC08614C4B38 (weak digest)
Confirming the bug here, I have the following on my machine: lib/apt/ lists/ppa. launchpad. net_git- core_ppa_ ubuntu_ dists_xenial_ InRelease: The repository is insufficiently signed by key E1DD270288B4E60 30699E45FA1715D 88E1DF1F24 (weak digest) lib/apt/ lists/ppa. launchpad. net_gnome3- team_gnome3_ ubuntu_ dists_xenial_ InRelease: The repository is insufficiently signed by key 9D542E3D52C801D 9F8E31682F1773A F13B1510FD (weak digest) lib/apt/ lists/ppa. launchpad. net_noobslab_ themes_ ubuntu_ dists_xenial_ InRelease: The repository is insufficiently signed by key 4FA44A478284A18 C1BA4A9CAD530E0 28F59EAE4D (weak digest) lib/apt/ lists/dl. google. com_linux_ chrome_ deb_dists_ stable_ Release. gpg: The repository is insufficiently signed by key 4CCA1EAF950CEE4 AB83976DCA04083 0F7FAC5991 (weak digest)
W: gpgv:/var/
W: gpgv:/var/
W: gpgv:/var/
W: gpgv:/var/
W: gpgv:/var/ lib/apt/ lists/ppa. launchpad. net_numix_ ppa_ubuntu_ dists_xenial_ InRelease: The repository is insufficiently signed by key 43E076121739DEE 5FB96BBED52B709 720F164EEB (weak digest) lib/apt/ lists/dl. google. com_linux_ earth_deb_ dists_stable_ Release. gpg: The repository is insufficiently signed by key 4CCA1EAF950CEE4 AB83976DCA04083 0F7FAC5991 (weak digest) lib/apt/ lists/ppa. launchpad. net_otto- kesselgulasch_ gimp-edge_ ubuntu_ dists_xenial_ InRelease: The repository is insufficiently signed by key FB97E9C3A97F85C 095AEA7903BDAAC 08614C4B38 (weak digest)
W: gpgv:/var/
W: gpgv:/var/