In 3.6 and 3.7 The Same Error is back on line 960 with gcc 6.3.0 on cygwin64. This issue is not entirely fixed even with the absolute latest commits.
$ make
gcc -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-pro
totypes -std=c99 -Wextra -Wno-unused-result -Wno-unused-parameter -Wno-missin
g-field-initializers -I. -I./Include -DPy_BUILD_CORE -c ./Modules/signalmo
dule.c -o Modules/signalmodule.o
In file included from ./Include/Python.h:85:0,
from ./Modules/signalmodule.c:6:
./Modules/signalmodule.c: In function ‘fill_siginfo’:
./Modules/signalmodule.c:960:60: error: ‘siginfo_t {aka struct <anonymous>}’ has
no member named ‘si_band’; did you mean ‘si_pid’?
PyStructSequence_SET_ITEM(result, 6, PyLong_FromLong(si->si_band));
^
./Include/tupleobject.h:62:75: note: in definition of macro ‘PyTuple_SET_ITEM’
#define PyTuple_SET_ITEM(op, i, v) (((PyTupleObject *)(op))->ob_item[i] = v)
^
./Modules/signalmodule.c:960:5: note: in expansion of macro ‘PyStructSequence_SE
T_ITEM’
PyStructSequence_SET_ITEM(result, 6, PyLong_FromLong(si->si_band));
^~~~~~~~~~~~~~~~~~~~~~~~~
make: *** [Makefile:1741: Modules/signalmodule.o] Error 1