Do not try to guess "docker" in Debian SysV init script
On boot, the init script is invoked from `/etc/rcN.d/S20docker` (where N
is the runlevel). Consequently, the init script tried to find the
defaults at `/etc/defaults/S20docker` and the binary at
`/usr/bin/S20docker`. This causes the docker daemon to fail at boot with
the error
/usr/bin/S20docker not present or not executable
Starting it manually works because it invokes `/etc/init.d/docker` which
has the correct basename.
Fix this by hardcoding "docker" as the base name.
Signed-off-by: Matthias Rampke <mr@soundcloud.com>
Matthias Rampke