nomad: builds failing for 10.12 and earlier: 'hclfmt' consistently crashes with SIGSEGV

[mascguy (Christopher Nielsen)]

This port fails to build for 10.12 and earlier, due to a consistent crash when running hclfmt:

--> Formatting HCL
fatal error: unexpected signal during runtime execution
[signal SIGSEGV: segmentation violation code=0x1 addr=0xb01dfacedebac1e pc=0x44688a5]

runtime stack:
runtime: unexpected return pc for runtime.sigpanic called from 0x44688a5
[...]
runtime.throw({0x41e4a55, 0x0})
	/opt/local/lib/go/src/runtime/panic.go:1198 +0x71
runtime: unexpected return pc for runtime.sigpanic called from 0x44688a5
[...]
goroutine 1 [syscall, locked to thread]:
syscall.syscall(0x419d0e0, 0x2, 0x40487413, 0xc0000cbd98)
	/opt/local/lib/go/src/runtime/sys_darwin.go:22 +0x3b fp=0xc0000cbd08 sp=0xc0000cbce8 pc=0x405cc1b
syscall.syscall(0x400dbd4, 0x10000c0000b1a40, 0x4ac0b30, 0x30)
	<autogenerated>:1 +0x26 fp=0xc0000cbd50 sp=0xc0000cbd08 pc=0x4062366
golang.org/x/sys/unix.ioctl(0x30, 0x4369d60, 0xc000099ef0)
	/opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_net_nomad/nomad/work/pkg/mod/golang.org/x/sys@v0.0.0-20190502175342-a43fa875dd82/unix/zsyscall_darwin_amd64.go:782 +0x39 fp=0xc0000cbd80 sp=0xc0000cbd50 pc=0x419cd79
golang.org/x/sys/unix.IoctlGetTermios(...)
	/opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_net_nomad/nomad/work/pkg/mod/golang.org/x/sys@v0.0.0-20190502175342-a43fa875dd82/unix/syscall_darwin.go:364
golang.org/x/crypto/ssh/terminal.IsTerminal(0xc0000cbe38)
	/opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_net_nomad/nomad/work/pkg/mod/golang.org/x/crypto@v0.0.0-20190426145343-a29dc8fdc734/ssh/terminal/util.go:30 +0x50 fp=0xc0000cbdf0 sp=0xc0000cbd80 pc=0x419d190
main.init.0()
	/opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_net_nomad/nomad/work/pkg/mod/github.com/hashicorp/hcl/v2@v2.5.1/cmd/hclfmt/main.go:33 +0x55 fp=0xc0000cbe48 sp=0xc0000cbdf0 pc=0x419d295
runtime.doInit(0x431f480)
	/opt/local/lib/go/src/runtime/proc.go:6498 +0x123 fp=0xc0000cbf80 sp=0xc0000cbe48 pc=0x40426e3
runtime.main()
	/opt/local/lib/go/src/runtime/proc.go:238 +0x1e6 fp=0xc0000cbfe0 sp=0xc0000cbf80 pc=0x40357c6
runtime.goexit()
	/opt/local/lib/go/src/runtime/asm_amd64.s:1581 +0x1 fp=0xc0000cbfe8 sp=0xc0000cbfe0 pc=0x405fe41
make: *** [hclfmt] Error 1

This is happening consistently on all of our buildbots, as well as locally on my macOS 10.12 install:

​https://ports.macports.org/port/nomad/builds/

[mascguy (Christopher Nielsen)]

Herby, any thoughts on this?