Test failure only on first run (triggered by gc?)

[Cody-G]

When I run tests just after installing ImageView on Julia 0.6 I get this error:

julia> include("runtests.jl")
Test Summary: | Pass  Total
contrast GUI  |    1      1
Error encountered while loading "/home/cody/Desktop/jpacks3/v0.6/TestImages/images/cameraman.tif".
Fatal error:
Library "ImageMagick" is not installed but is recommended as a library to load format: ".tif"
Should we install "ImageMagick" for you? (y/n):
y
INFO: Start installing ImageMagick...
INFO: Installing ImageMagick v0.5.2
INFO: Building FFTW
INFO: Building SpecialFunctions
INFO: Building ImageMagick
INFO: Package database updated
ERROR: LoadError: LoadError: MethodError: no method matching getindex(::Void, ::UnitRange{Int64}, ::UnitRange{Int64})
Stacktrace:
 [1] include_from_node1(::String) at ./loading.jl:576
 [2] include(::String) at ./sysimg.jl:14
 [3] include_from_node1(::String) at ./loading.jl:576
 [4] include(::String) at ./sysimg.jl:14
while loading /home/cody/Desktop/jpacks3/v0.6/ImageView/test/scalesigned.jl, in expression starting on line 16
while loading /home/cody/Desktop/jpacks3/v0.6/ImageView/test/runtests.jl, in expression starting on line 3

If I run the tests again they pass. The only way I've found to trigger the error again is to uninstall ImageMagick, close julia, reopen julia, and run the tests again. See also discussion in #145

Also note the line number in scalesigned.jl shown in the stacktrace is 16 for me because I tried adding gc() statements to force the error. The line number on master is 6.

[timholy]

Tests do not fail on master with 0.6, see #152. I can't get it to fail locally either.