Bug#839686: forked-daapd: does not recreate stuff in /var/cache after deletion

[Dominik George]

Package: forked-daapd
Version: 24.1-1+b1
Severity: serious
Justification: Policy 9.1.1

After deleting /var/cache/forked-daapd, forked-daapd cannot start up
again because it fails to open the database.

forked-daapd seems to require its data files there, while the FHS
unmistakably states:

"Unlike /var/spool, the cached files can be deleted without data loss.
The data must remain valid between invocations of the application and
rebooting the system.

Files located under /var/cache may be expired in an application specific
manner, by the system administrator, or both. The application must
always be able to recover from manual deletion of these files (generally
because of a disk space shortage). No other requirements are made on the
data format of the cache directories."

Please note that while the below information states this is Raspbian, I
can assure that forked-daapd and all its dependencies on this system are
plain Debian armhf ☺.

-- System Information:
Distributor ID:	Raspbian
Description:	Raspbian GNU/Linux testing (stretch)
Release:	testing
Codename:	stretch
Architecture: armv7l

Kernel: Linux 4.4.21-v7+ (SMP w/4 CPU cores)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages forked-daapd depends on:
ii  adduser             3.115
ii  avahi-daemon        0.6.32-1
ii  libantlr3c-3.2-0    3.2-3
ii  libasound2          1.1.2-1
ii  libavahi-client3    0.6.32-1
ii  libavahi-common3    0.6.32-1
ii  libavcodec-extra57  7:3.1.3-1+b3
ii  libavfilter6        7:3.1.3-1+b3
ii  libavformat57       7:3.1.3-1+b3
ii  libavutil55         7:3.1.3-1+b3
ii  libc6               2.24-3
ii  libconfuse1         3.0+dfsg-2
ii  libcurl3-gnutls     7.50.1-1
ii  libevent-2.0-5      2.0.21-stable-2+b1
ii  libgcrypt20         1.7.3-1
ii  libgnutls30         3.5.4-2
ii  libgpg-error0       1.24-1
ii  libjson-c3          0.12.1-1
ii  libmxml1            2.10-1
ii  libplist3           1.12-3.1
ii  libprotobuf-c1      1.2.1-1+b1
ii  libsqlite3-0        3.14.2-1
ii  libswscale4         7:3.1.3-1+b3
ii  libunistring0       0.9.6+really0.9.3-0.1
ii  psmisc              22.21-2.1
ii  zlib1g              1:1.2.8.dfsg-2+b1

Versions of packages forked-daapd recommends:
ii  libavcodec-extra                       7:3.1.3-1
ii  libavcodec-extra57 [libavcodec-extra]  7:3.1.3-1+b3

forked-daapd suggests no packages.

-- Configuration Files:
/etc/forked-daapd.conf changed [not included]

-- no debconf information