Remove noisy debug log for missing version (#1703)
Remove noisy debug log for missing version (#1703)

Users that build bazel from source (perhaps because they want to pin the bazel version via a submodule or other means) will not have a bazel version present ever.

This means every single bazel command will print out the following debug lines, which are mostly noise, since those users are probably aware they have built bazel from source. 

>DEBUG: /private/var/tmp/_bazel_jgavris/c1e7067b81f8f6fa16df07b65cd39d9c/external/io_bazel_rules_go/go/private/skylib/lib/versions.bzl:98:7:
Current Bazel is not a release version, cannot check for compatibility.
DEBUG: /private/var/tmp/_bazel_jgavris/c1e7067b81f8f6fa16df07b65cd39d9c/external/io_bazel_rules_go/go/private/skylib/lib/versions.bzl:99:7: Make sure that you are running at least Bazel 0.8.0.
Xjs/rules_go,Xjs/rules_go,Xjs/rules_go,Xjs/rules_go,bazelbuild/rules_go,bazelbuild/rules_go,bazelbuild/rules_go,bazelbuild/rules_go,Xjs/rules_go,bazelbuild/rules_go