Breakage is due to this change in go 1.12:
Tracebacks, runtime.Caller, and runtime.Callers no longer include compiler-generated initialization functions. Doing a traceback during the initialization of a global variable will now show a function named PKG.init.ializers.
Fix#137
* Add Go 1.10 to .travis.yml.
* Add quotes to Go versions in .travis.yml, because unquoted 1.10 is interpreted
as Go 1.1.
* Change .travis.yml references from 'tip' to 'master'. 'tip' is a legacy reference
coming from the days when the Go project used mercurial instead of git.