we've recently updated Imagemagick in NixOS from version 6.9.7-6 to 6.9.8-4, and this change causes the Ikiwiki test suite to fail in t/img.t, like so:

#   Failed test at t/img.t line 119.
#          got: 'no image'
#     expected: '10x10'

#   Failed test at t/img.t line 129.
#          got: 'no image'
#     expected: '12x12'

#   Failed test at t/img.t line 130.
#          got: 'no image'
#     expected: '16x2'

#   Failed test at t/img.t line 134.
#          got: 'no image'
#     expected: '8x8'

#   Failed test at t/img.t line 135.
#          got: 'no image'
#     expected: '4x4'

#   Failed test at t/img.t line 136.
#          got: 'no image'
#     expected: '6x6'

#   Failed test at t/img.t line 138.
#          got: 'no image'
#     expected: '11x11'

#   Failed test at t/img.t line 139.
#          got: 'no image'
#     expected: '12x12'

#   Failed test at t/img.t line 140.
#          got: 'no image'
#     expected: '13x13'
# Looks like you failed 9 tests of 62.
t/img.t ........................
Dubious, test returned 9 (wstat 2304, 0x900)
Failed 9/62 subtests

Is this is a known problem and is there maybe a fix for this issue?

This was not a known bug before your report. It looks as though every time we use Image::Magick->Read(":foo.png"), which is (or was) ImageMagick's syntax for opening a file of unknown type without interpreting a prefix containing : as a special directive instead of part of the filename, it fails.

Please try re-running the test with better diagnostics using commit 4ace7dbb7 and report what it says. --smcv

I see the same issue on Fedora, with ImageMagic 6.9.9-19:

#   Failed test at t/img.t line 119.
#          got: 'no image: Exception 435: unable to open image `:t/tmp/out/imgconversions/10x-redsquare.png': No such file or directory @ error/blob.c/OpenBlob/2701'
#     expected: '10x10'
[...]

So it seems, that an empty coder prefix is not accepted anymore. To me it seems that this commit changed the behavior. Unfortunately, the commit message doens't tell us about the reasons behind. The commit is included from version 6.9.8-3 on.

This should now be fixed in git and in the next release. The test failure does not indicate a loss of functionality, unless you are using uncommon image formats enabled with img_allowed_formats: [everything], which is a potential security vulnerability because it exposes the attack surface of all ImageMagick decoder modules. --smcv