This was fixed in initramfs-tools version 0.123 which is available in Zesty and later releases. The fix should be SRU'ed to both Ubuntu 14.04 and Ubuntu 16.04 which are affected. Here's a link to the commit which fixed this:
https://anonscm.debian.org/cgit/kernel/initramfs-tools.git/commit/?id=ac6d31fc2c707b72ff8af9944c9b4f8af303a6a3
This was fixed in initramfs-tools version 0.123 which is available in Zesty and later releases. The fix should be SRU'ed to both Ubuntu 14.04 and Ubuntu 16.04 which are affected. Here's a link to the commit which fixed this:
https:/ /anonscm. debian. org/cgit/ kernel/ initramfs- tools.git/ commit/ ?id=ac6d31fc2c7 07b72ff8af9944c 9b4f8af303a6a3