-getRed:green:blue:alpha: not defined for the NSColor

[Keith David Bershatsky]

I have several older Apple machines running OSX 10.6.8 and only one newer 
machines with El Capitan (which I no longer use for a variety of reasons).  
Between the dates of 04/08/2019 and 07/10/2019, change(s) to the master branch 
broke the ability to use Emacs.  I get a welcome screen and gdb spams me with 
the following messages:

2019-07-12 14:36:27.976 Emacs[74347:60f] *** -getRed:green:blue:alpha: not 
defined for the NSColor NSCustomColorSpace Device RGB colorspace 0 0 0 1; need 
to first convert colorspace.

If possible, it would be wonderful if Emacs master branch could still support 
users with older computers running outdated operating systems; e.g., OSX 10.6.8.

If support for OSX 10.6.8 is no longer possible, then it would be greatly 
appreciated if someone can please point me to which commit(s) created this 
issue and some advice regarding how I can at least fix it on my end.  The 
average Emacs build time is in excess of 30 minutes due to all the 
byte-compiling and it would likely take me a very long time to locate the 
commit by trial and error; e.g., building various versions of Emacs from 
04/08/2019 to the present until the culprit is located.

My build options are as follows:

CFLAGS='-Wall -O0 -g3' ./configure \
--with-ns \
--enable-checking='yes,glyphs' \
--enable-check-lisp-object-type \
--without-compress-install \
--without-makeinfo \
--with-gnutls=no \
--with-mailutils \
--without-makeinfo

Thanks,

Keith