http://buildbot.python.org/all/#/builders/47/builds/127

(...)
gcc -pthread -c -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes    -std=c99 -Wextra -Wno-unused-result -Wno-unused-parameter -Wno-missing-field-initializers -Werror=implicit-function-declaration -fprofile-use -fprofile-correction  -I. -I./Include    -DPy_BUILD_CORE -o Objects/setobject.o Objects/setobject.c
Objects/setobject.c: In function ‘PySet_Clear’:
Objects/setobject.c:2579:1: internal compiler error: in create_edge, at cgraph.c:850
 };
 ^
Please submit a full bug report,
with preprocessed source if appropriate.
See <file:///usr/share/doc/gcc-6/README.Bugs> for instructions.
Makefile:1584: recipe for target 'Objects/setobject.o' failed
make[1]: Leaving directory '/var/lib/buildbot/slaves/enable-optimizations-bot/3.x.gps-debian-profile-opt.nondebug/build'
make[1]: *** [Objects/setobject.o] Error 1


pythoninfo from the previous build:

* GCC 6.3.0 20170516
* os.uname: posix.uname_result(sysname='Linux', nodename='enable-optimizations-bot', release='4.9.0-3-amd64', version='#1 SMP Debian 4.9.30-2+deb9u2 (2017-06-26)', machine='x86_64')
* platform.platform: Linux-4.9.0-3-amd64-x86_64-with-debian-9.1

http://buildbot.python.org/all/#/builders/47/builds/126/steps/3/logs/stdio