Change effective on 19 October 2016
Heroku’s support for Go has been upgraded to include Go 1.7.3. Future deploys with a
go1.7 specifier will use this new version.
go1.7.3 (released 2016/10/19) includes fixes to the compiler, runtime, and the crypto/cipher, crypto/tls, net/http, and strings packages. See the Go 1.7.3 milestone in the Go issue tracker for details.