Use ImageMagick 6 in Jenkins X Platform builders

2019-10-21 13:36:21,800 [main] ERROR [IMImageUtils$ImageMagickCaller] ImageMagick failed on command: resizer
org.nuxeo.ecm.platform.commandline.executor.api.CommandException: Error code 1 return by command: convert -define registry:temporary-path=#{nuxeo.tmp.dir} -quiet -background white -flatten -depth #{targetDepth} #{inputFilePath}[0] jpg:- | convert - -resize #{targetWidth}x#{targetHeight} #{outputFilePath}
convert: Corrupt JPEG data: 19 extraneous bytes before marker 0xd9 `/home/jenkins/workspace/nuxeo_nuxeo_master/nuxeo-features/nuxeo-platform-imaging/nuxeo-platform-imaging-core/target/nxruntime-main-9494129582169672659.tmp/tmp/magick-42111J3aBqYHiFfJZ' @ warning/jpeg.c/JPEGWarningHandler/399.
    at org.nuxeo.ecm.platform.commandline.executor.api.ExecResult.<init>(ExecResult.java:62) ~[classes/:?]
    at org.nuxeo.ecm.platform.commandline.executor.service.executors.ShellExecutor.exec(ShellExecutor.java:76) ~[classes/:?]
    at org.nuxeo.ecm.platform.commandline.executor.service.CommandLineExecutorComponent.execCommand(CommandLineExecutorComponent.java:173) ~[classes/:?]
    at org.nuxeo.ecm.platform.picture.magick.utils.ImageResizer.resize(ImageResizer.java:69) ~[classes/:?]
    at org.nuxeo.ecm.platform.picture.core.im.IMImageUtils$2.callImageMagick(IMImageUtils.java:157) ~[classes/:?]
    at org.nuxeo.ecm.platform.picture.core.im.IMImageUtils$ImageMagickCaller.call(IMImageUtils.java:67) [classes/:?]
    at org.nuxeo.ecm.platform.picture.core.im.IMImageUtils.resize(IMImageUtils.java:159) [classes/:?]
    at org.nuxeo.ecm.platform.picture.ImagingComponent.resize(ImagingComponent.java:107) [classes/:?]
    at org.nuxeo.ecm.platform.picture.convert.ResizePictureConverter.convert(ResizePictureConverter.java:65) [classes/:?]
    at org.nuxeo.ecm.core.convert.service.ConversionServiceImpl.convert(ConversionServiceImpl.java:339) [classes/:?]
    at org.nuxeo.ecm.platform.picture.operation.PictureResize.run(PictureResize.java:106) [classes/:?]
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?]
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:?]
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
    at java.lang.reflect.Method.invoke(Method.java:566) ~[?:?]
    at org.nuxeo.ecm.automation.core.impl.InvokableMethod.doInvoke(InvokableMethod.java:175) [classes/:?]
    at org.nuxeo.ecm.automation.core.impl.InvokableMethod.invoke(InvokableMethod.java:180) [classes/:?]
    at org.nuxeo.ecm.automation.core.impl.OperationChainCompiler$OperationMethod.invoke(OperationChainCompiler.java:151) [classes/:?]
    at org.nuxeo.ecm.automation.core.impl.OperationChainCompiler$CompiledChainImpl.lambda$invoke$0(OperationChainCompiler.java:218) [classes/:?]
    at org.nuxeo.ecm.automation.OperationContext.call(OperationContext.java:326) [classes/:?]
    at org.nuxeo.ecm.automation.OperationContext.callWithChainParameters(OperationContext.java:291) [classes/:?]
    at org.nuxeo.ecm.automation.core.impl.OperationChainCompiler$CompiledChainImpl.invoke(OperationChainCompiler.java:215) [classes/:?]
    at org.nuxeo.ecm.automation.core.impl.OperationServiceImpl.run(OperationServiceImpl.java:115) [classes/:?]
    at org.nuxeo.ecm.platform.picture.core.test.TestPictureResize.testResizer(TestPictureResize.java:98) [test-classes/:?]