Bug#826721: gnuplot-x11: update-alternatives: error: alternative link /usr/share/gnuplot/gnuplot.gih is already managed by gnuplot4

[Sven Joachim]

Package: gnuplot-x11
Version: 5.0.3+dfsg3-1
Severity: serious

Your package failed to configure:

,----
| # LANG=C dpkg --configure --pending
| Setting up gnuplot-x11 (5.0.3+dfsg3-1) ...
| update-alternatives: error: alternative link /usr/share/gnuplot/gnuplot.gih is already managed by gnuplot4
| dpkg: error processing package gnuplot-x11 (--configure):
|  subprocess installed post-installation script returned error exit status 2
| Errors were encountered while processing:
|  gnuplot-x11
`----

There is a file gnuplot4 in /var/lib/dpkg/alternatives dated 2015-08-27
which contains alternatives for gnuplot4:

,----
| auto
| /usr/bin/gnuplot4
| gnuplot4.1.gz
| /usr/share/man/man1/gnuplot4.1.gz
| gnuplot4.gih
| /usr/share/gnuplot/gnuplot.gih
| 
| /usr/bin/gnuplot4-x11
| 30
| /usr/share/man/man1/gnuplot4-x11.1.gz
| /usr/share/gnuplot/gnuplot4-x11.gih
`----

AFAICS these alternatives were set up by the previous version (4.6.6-3)
of gnuplot-x11 which does not remove them on upgrades, so gnuplot-x11's
responsibility is to remove them in the new postinst.


-- System Information:
Debian Release: stretch/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (101, 'experimental')
Architecture: i386 (x86_64)

Kernel: Linux 4.6.2-nouveau (SMP w/2 CPU cores)
Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages gnuplot-x11 depends on:
ii  gnuplot-data         5.0.3+dfsg3-1
ii  libc6                2.22-11
ii  libcairo2            1.14.6-1+b1
ii  libedit2             3.1-20150325-1+b1
ii  libgcc1              1:6.1.1-5
ii  libgd3               2.2.1-1
ii  libglib2.0-0         2.48.1-1
ii  liblua5.1-0          5.1.5-8
ii  libpango-1.0-0       1.40.1-1
ii  libpangocairo-1.0-0  1.40.1-1
ii  libstdc++6           6.1.1-5
ii  libwxbase3.0-0v5     3.0.2+dfsg-1.4
ii  libwxgtk3.0-0v5      3.0.2+dfsg-1.4
ii  libx11-6             2:1.6.3-1

gnuplot-x11 recommends no packages.

Versions of packages gnuplot-x11 suggests:
ii  gnuplot-doc  5.0.3+dfsg3-1

-- no debconf information