7.2.0 says "Bootstrap comparison failure!" on entering stage3

[dclarke@blastwave.org]

Hello all. 

This is fascinating in that it seems to be quite emphatic in the message
: 

.
.
.
rm -f stage_current
gmake[3]: Leaving directory
'/usr/local/build/gcc-7.2.0_SunOS5.10_sparc64vii+.002'
Comparing stages 2 and 3
warning: gcc/cc1obj-checksum.o differs
warning: gcc/cc1-checksum.o differs
warning: gcc/cc1objplus-checksum.o differs
warning: gcc/cc1plus-checksum.o differs
Bootstrap comparison failure!
gcc/cfganal.o differs
gcc/vec.o differs
.
.
. many many lines about other "differs"
.
.
.
zlib/libz_a-gzwrite.o differs
zlib/libz_a-gzread.o differs
gmake[2]: *** [Makefile:28094: compare] Error 1
gmake[2]: Leaving directory
'/usr/local/build/gcc-7.2.0_SunOS5.10_sparc64vii+.002'
gmake[1]: *** [Makefile:28074: stage3-bubble] Error 2
gmake[1]: Leaving directory
'/usr/local/build/gcc-7.2.0_SunOS5.10_sparc64vii+.002'
gmake: *** [Makefile:28137: bootstrap] Error 2

So .. wow.

Could this be because I have different stage languages and
stage1-checking selected? 

    --enable-languages=ada,c,c++,fortran,go,objc,obj-c++ 
    --enable-stage1-languages=c,c++ 
    --enable-stage1-checking=misc 

or perhaps some other mystery ? 

Dennis