I just learned about go mod tidy

go.mod

@@ -4,7 +4,6 @@ go 1.12
 
 require (
 	github.com/BurntSushi/toml v0.3.1 // indirect
-	github.com/caddyserver/builds v0.0.0-20170910200810-c62e2219460a
 	github.com/dustin/go-humanize v1.0.0
 	github.com/flynn/go-shlex v0.0.0-20150515145356-3f9db97f8568
 	github.com/go-acme/lego v2.5.0+incompatible

go.sum

@@ -2,8 +2,6 @@ github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/bifurcation/mint v0.0.0-20180715133206-93c51c6ce115 h1:fUjoj2bT6dG8LoEe+uNsKk8J+sLkDbQkJnB6Z1F02Bc=
 github.com/bifurcation/mint v0.0.0-20180715133206-93c51c6ce115/go.mod h1:zVt7zX3K/aDCk9Tj+VM7YymsX66ERvzCJzw8rFCX2JU=
-github.com/caddyserver/builds v0.0.0-20170910200810-c62e2219460a h1:/QF4JSis49aT5EttkyiWjj8EQ/HvTLoVF0C90mD3oEY=
-github.com/caddyserver/builds v0.0.0-20170910200810-c62e2219460a/go.mod h1:+ku9jD54BwZiFQSoYXMc18iQ5u3eED8Mvd174cZno3Q=
 github.com/cenkalti/backoff v2.1.1+incompatible h1:tKJnvO2kl0zmb/jA5UKAt4VoEVw1qxKWjE/Bpp46npY=
 github.com/cenkalti/backoff v2.1.1+incompatible/go.mod h1:90ReRw6GdpyfrHakVjL/QHaoyV4aDUVVkXQJJJ3NXXM=
 github.com/cheekybits/genny v0.0.0-20170328200008-9127e812e1e9 h1:a1zrFsLFac2xoM6zG1u72DWJwZG3ayttYLfmLbxVETk=
@@ -16,9 +14,6 @@ github.com/flynn/go-shlex v0.0.0-20150515145356-3f9db97f8568 h1:BHsljHzVlRcyQhjr
 github.com/flynn/go-shlex v0.0.0-20150515145356-3f9db97f8568/go.mod h1:xEzjJPgXI435gkrCt3MPfRiAkVrwSbHsst4LCFVfpJc=
 github.com/fsnotify/fsnotify v1.4.7 h1:IXs+QLmnXW2CcXuY+8Mzv/fWEsPGWxqefPtCP5CnV9I=
 github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
-github.com/go-acme/lego v2.3.1-0.20190318164254-3684cc738d37+incompatible/go.mod h1:yzMNe9CasVUhkquNvti5nAtPmG94USbYxYrZfTkIn0M=
-github.com/go-acme/lego v2.4.0+incompatible h1:+BTLUfLtDc5qQauyiTCXH6lupEUOCvXyGlEjdeU0YQI=
-github.com/go-acme/lego v2.4.0+incompatible/go.mod h1:yzMNe9CasVUhkquNvti5nAtPmG94USbYxYrZfTkIn0M=
 github.com/go-acme/lego v2.5.0+incompatible h1:5fNN9yRQfv8ymH3DSsxla+4aYeQt2IgfZqHKVnK8f0s=
 github.com/go-acme/lego v2.5.0+incompatible/go.mod h1:yzMNe9CasVUhkquNvti5nAtPmG94USbYxYrZfTkIn0M=
 github.com/golang/mock v1.2.0 h1:28o5sBqPkBsMGnC6b4MvE2TzSr5/AT4c/1fLqVGIwlk=
@@ -49,8 +44,6 @@ github.com/lucas-clemente/quic-go v0.10.2/go.mod h1:hvaRS9IHjFLMq76puFJeWNfmn+H7
 github.com/lucas-clemente/quic-go-certificates v0.0.0-20160823095156-d2f86524cced h1:zqEC1GJZFbGZA0tRyNZqRjep92K5fujFtFsu5ZW7Aug=
 github.com/lucas-clemente/quic-go-certificates v0.0.0-20160823095156-d2f86524cced/go.mod h1:NCcRLrOTZbzhZvixZLlERbJtDtYsmMw8Jc4vS8Z0g58=
 github.com/marten-seemann/qtls v0.2.3/go.mod h1:xzjG7avBwGGbdZ8dTGxlBnLArsVKLvwmjgmPuiQEcYk=
-github.com/mholt/certmagic v0.0.0-20190319183800-ee1543e2f234 h1:6biVHmhBIOQCzdOClOJ97D/Ip9oH8TgFftq2bj/93YI=
-github.com/mholt/certmagic v0.0.0-20190319183800-ee1543e2f234/go.mod h1:KvmxBmeVqj88J9Z9us/x04Yp/YYfMtmGkhQFWewFe6U=
 github.com/mholt/certmagic v0.5.0 h1:lYXxsLUFya/I3BgDCrfuwcMQOB+4auzI8CCzpK41tjc=
 github.com/mholt/certmagic v0.5.0/go.mod h1:g4cOPxcjV0oFq3qwpjSA30LReKD8AoIfwAY9VvG35NY=
 github.com/miekg/dns v1.1.3 h1:1g0r1IvskvgL8rR+AcHzUA+oFmGcQlaIm4IqakufeMM=