Using "github.com/go-ldap/ldap" in import, go build spits out
go: downloading gopkg.in/asn1-ber.v1 v1.3.1
build trying: cannot load gopkg.in/asn1-ber.v1: cannot find module providing package gopkg.in/asn1-ber.v1

Importing instead with gopkg.in/ldap.v3, fails with

go: downloading gopkg.in/ldap.v3 v3.1.1
build trying: cannot load gopkg.in/ldap.v3: cannot find module providing package gopkg.in/ldap.v3

Basically gopkg seems to be failing in either case.