Go 1.7 will have context in the standard library. The golang.org/x/net package has a build tag for go 1.7 and that file depends on the standard library version of context.

Glide looking at all the packages across all the build flags has a problem with this.

See golang/net@afc22ee#diff-22b1e0bcbf56beea47fa8ad88e890286R5