Occasionally getting jsonnet_cgo based go runtime panics

[mlieberman85]

One out of every 5 or so runs of a test I am doing where I evaluate a few jsonnet files, in parallel using go routines.

I believe I'm using the latest version of your code.
Go 1.8.3
MacOS Sierra

Pertinent section of the trace:

SIGTRAP: trace trap
PC=0x4050102 m=3 sigcode=1
signal arrived during cgo execution

goroutine 5 [syscall, locked to thread]:
runtime.cgocall(0x40ccc90, 0xc42003ed18, 0xc42003ed40)
        /usr/local/Cellar/go/1.8.3/libexec/src/runtime/cgocall.go:131 +0xe2 fp=0xc42003ece8 sp=0xc42003eca8
github.com/strickyak/jsonnet_cgo._Cfunc_jsonnet_evaluate_file(0x5c08bb0, 0x5c08cc0, 0xc42009e010, 0x0)
        github.com/strickyak/jsonnet_cgo/_obj/_cgo_gotypes.go:112 +0x4e fp=0xc42003ed18 sp=0xc42003ece8
github.com/strickyak/jsonnet_cgo.(*VM).EvaluateFile.func2(0x5c08bb0, 0x5c08cc0, 0xc42009e010, 0xc42003ed98)
        /Users/michaellieberman/godeps/src/github.com/strickyak/jsonnet_cgo/jsonnet.go:172 +0x74 fp=0xc42003ed50 sp=0xc42003ed18
github.com/strickyak/jsonnet_cgo.(*VM).EvaluateFile(0xc42009e000, 0xc42001e300, 0x53, 0x0, 0x0, 0x0, 0x0)
        /Users/michaellieberman/godeps/src/github.com/strickyak/jsonnet_cgo/jsonnet.go:172 +0xd2 fp=0xc42003eda8 sp=0xc42003ed50