openafs-client's systemd unit's EnvironmentFile /var/cache/openafs-client/openafs-client.env is overwritten at every reboot

[Karl-Philipp Richter]

The `systemd` unit `/lib/systemd/system/openafs-client.service` uses the `EnvironmentFile` directive to get argument to append to `afsd` from `/var/cache/openafs-client/openafs-client.env` which is overwritten with the initial state at every reboot for no obvious reason. If such reason exist a warning in form of a connection should be added to the file because it's quite uncommon for a `systemd` unit to reset changes at reboot.

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: openafs-client 1.6.14-1
Uname: Linux 4.2.5-040205-generic x86_64
NonfreeKernelModules: openafs zfs zunicode zcommon znvpair zavl
ApportVersion: 2.19.1-0ubuntu5
Architecture: amd64
Date: Fri Feb 12 21:25:34 2016
InstallationDate: Installed on 2015-04-20 (298 days ago)
InstallationMedia: Ubuntu-Server 14.10 "Utopic Unicorn" - Release amd64 (20141022.2)
ProcEnviron:
 TERM=screen
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: openafs
UpgradeStatus: Upgraded to wily on 2015-10-26 (109 days ago)