[DRE-maint] Bug#733723: ruby-rmagick: FTBFS on i386: stroke_linecap.rb:42:in `draw': pixels are not authentic

[Christian Hofstaedtler]

Package: ruby-rmagick
Version: 2.13.2-1
Severity: serious
Justification: fails to build from source (but built successfully in the past)

Dear Maintainer,

ruby-rmagick failed to build from source on i386.

Excerpt from https://buildd.debian.org/status/fetch.php?pkg=ruby-rmagick&arch=i386&ver=2.13.2-1&stamp=1380584926

> /usr/bin/ruby1.9.1 -I /«PKGBUILDDIR»/./lib -I /«PKGBUILDDIR»/./ext/RMagick stroke_dasharray.rb (example 154 of 188)
> /«PKGBUILDDIR»/lib/RMagick.rb:1836: warning: assigned but unused variable - current
> /usr/bin/ruby1.9.1 -I /«PKGBUILDDIR»/./lib -I /«PKGBUILDDIR»/./ext/RMagick stroke_fill.rb (example 155 of 188)
> /«PKGBUILDDIR»/lib/RMagick.rb:1836: warning: assigned but unused variable - current
> /usr/bin/ruby1.9.1 -I /«PKGBUILDDIR»/./lib -I /«PKGBUILDDIR»/./ext/RMagick stroke_linecap.rb (example 156 of 188)
> /«PKGBUILDDIR»/lib/RMagick.rb:1836: warning: assigned but unused variable - current
> stroke_linecap.rb:42:in `draw': pixels are not authentic `' @ error/cache.c/QueueAuthenticPixelCacheNexus/4387 (Magick::ImageMagickError)
>                        from stroke_linecap.rb:42:in `<main>'
> setup.rb:             Too many examples failed. Search for "Help!" at
>             http://rmagick.rubyforge.org/install-faq.html.
> post-setup.rb: stroke_linecap.rb example returned error code pid 19738 exit 1

This build failure has delayed migration to testing for 91 days.

Christian