magick xc:black black.pnm creates a white image

[cjmayo]

Prerequisites

• I have written a descriptive issue title
• I have verified that I am using the latest version of ImageMagick
• I have searched open and closed issues to ensure it has not already been reported

Description

Fix from #1632 resolved issue with:
magick -size 100x100 xc:white white.pnm
but broke:
magick -size 100x100 xc:black black.pnm
which now creates a white image.

Steps to Reproduce

1. magick -size 100x100 xc:black black.pnm
2. View black.pnm and see it is white instead of the expected black

System Configuration

• ImageMagick version: 7.0.8-53 +

--- a/coders/pnm.c
+++ b/coders/pnm.c
@@ -1944,7 +1944,7 @@ static MagickBooleanType WritePNMImage(const ImageInfo *image_info,Image *image,
         if (quantum_info == (QuantumInfo *) NULL)
           ThrowWriterException(ResourceLimitError,"MemoryAllocationFailed");
         (void) SetQuantumEndian(image,quantum_info,MSBEndian);
-        quantum_info->min_is_white=MagickTrue;
+        quantum_info->min_is_white=MagickFalse;
         pixels=GetQuantumPixels(quantum_info);
         for (y=0; y < (ssize_t) image->rows; y++)
         {

• Environment (Operating system, version and so on): Gentoo Linux
• Additional information:

[urban-warrior]

Thanks for the problem report. We can reproduce it and will have a patch to fix it in GIT master branch @ https://github.com/ImageMagick/ImageMagick later today. The patch will be available in the beta releases of ImageMagick @ http://www.imagemagick.org/download/beta/ by sometime tomorrow.