Bug#869846: dose-builddebcheck: plural error in error message

[Wookey <wookey@debian.org>]

Package: dose-builddebcheck
Version: 5.0.1-8
Severity: minor

A minor nit.

I got this error message due to giving dose-builddebcheck a duff filename:
Fatal error in module common/input.ml: 
 Input file /var/lib/apt/lists/*_main_binary-amd64_Packages does not exists.
dose-builddebcheck failed with error code 64

'does not exists' is wrong. Should be 'does not exist'.

-- System Information:
Debian Release: 8.9
  APT prefers oldstable-updates
  APT policy: (500, 'oldstable-updates'), (500, 'oldstable')
Architecture: amd64 (x86_64)

Kernel: Linux 3.16.0-4-amd64 (SMP w/8 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)