Upgrade to latest go-github

Hopefully this fixes the spurious 502s we see on cs.bazel.build

Change-Id: Ica9eb848a68cd929bff310c3c3c3a57907c5d6d3
diff --git a/cmd/zoekt-mirror-github/main.go b/cmd/zoekt-mirror-github/main.go
index b43e555..c1848ca 100644
--- a/cmd/zoekt-mirror-github/main.go
+++ b/cmd/zoekt-mirror-github/main.go
@@ -30,7 +30,7 @@
 	"strconv"
 	"strings"
 
-	"github.com/google/go-github/github"
+	"github.com/google/go-github/v27/github"
 	"golang.org/x/oauth2"
 
 	"github.com/google/zoekt/gitindex"
diff --git a/go.mod b/go.mod
index defd494..34be423 100644
--- a/go.mod
+++ b/go.mod
@@ -5,14 +5,14 @@
 	github.com/fsnotify/fsnotify v1.4.7
 	github.com/gfleury/go-bitbucket-v1 v0.0.0-20181102191809-4910839b609e
 	github.com/google/go-cmp v0.3.0
-	github.com/google/go-github v17.0.0+incompatible
+	github.com/google/go-github/v27 v27.0.4
 	github.com/google/slothfs v0.0.0-20170112234537-ecdd255f653d
 	github.com/kylelemons/godebug v0.0.0-20170820004349-d65d576e9348
 	github.com/mitchellh/mapstructure v1.1.2 // indirect
 	github.com/xanzy/go-gitlab v0.13.0
 	go.uber.org/automaxprocs v1.2.0
-	golang.org/x/net v0.0.0-20181114220301-adae6a3d119a
+	golang.org/x/net v0.0.0-20190311183353-d8887717615a
 	golang.org/x/oauth2 v0.0.0-20181120190819-8f65e3013eba
-	golang.org/x/sync v0.0.0-20181108010431-42b317875d0f
+	golang.org/x/sync v0.0.0-20190227155943-e225da77a7e6
 	gopkg.in/src-d/go-git.v4 v4.8.0
 )
diff --git a/go.sum b/go.sum
index 3a2563e..dea4023 100644
--- a/go.sum
+++ b/go.sum
@@ -24,6 +24,8 @@
 github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
 github.com/google/go-github v17.0.0+incompatible h1:N0LgJ1j65A7kfXrZnUDaYCs/Sf4rEjNlfyDHW9dolSY=
 github.com/google/go-github v17.0.0+incompatible/go.mod h1:zLgOLi98H3fifZn+44m+umXrS52loVEgC2AApnigrVQ=
+github.com/google/go-github/v27 v27.0.4 h1:N/EEqsvJLgqTbepTiMBz+12KhwLovv6YvwpRezd+4Fg=
+github.com/google/go-github/v27 v27.0.4/go.mod h1:/0Gr8pJ55COkmv+S/yPKCczSkUPIM/LnFyubufRNIS0=
 github.com/google/go-querystring v1.0.0 h1:Xkwi/a1rcvNg1PPYe5vI8GbeBY/jrVuDX5ASuANWTrk=
 github.com/google/go-querystring v1.0.0/go.mod h1:odCYkC5MyYFN7vkCjXpyrEuKhc/BUO6wN/zVPAxq5ck=
 github.com/google/slothfs v0.0.0-20170112234537-ecdd255f653d h1:ADHffp2KLaMypb4pG5pBJ8AezYRvGxQQ8vnH0E1K04c=
@@ -64,20 +66,30 @@
 go.uber.org/automaxprocs v1.2.0/go.mod h1:YfO3fm683kQpzETxlTGZhGIVmXAhaw3gxeBADbpZtnU=
 golang.org/x/crypto v0.0.0-20180904163835-0709b304e793 h1:u+LnwYTOOW7Ukr/fppxEb1Nwz0AtPflrblfvUudpo+I=
 golang.org/x/crypto v0.0.0-20180904163835-0709b304e793/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2 h1:VklqNMn3ovrHsnt90PveolxSbWFaJdECFbxSq0Mqo2M=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20180906233101-161cd47e91fd/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20181108082009-03003ca0c849/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20181114220301-adae6a3d119a h1:gOpx8G595UYyvj8UK4+OFyY4rx037g3fmfhe5SasG3U=
 golang.org/x/net v0.0.0-20181114220301-adae6a3d119a/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
+golang.org/x/net v0.0.0-20190311183353-d8887717615a h1:oWX7TPOiFAMXLq8o0ikBYfCJVlRHBcsciT5bXOrH628=
+golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.0.0-20181106182150-f42d05182288/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.0.0-20181120190819-8f65e3013eba h1:YDkOrzGLLYybtuP6ZgebnO4OWYEYVMFSniazXsxrFN8=
 golang.org/x/oauth2 v0.0.0-20181120190819-8f65e3013eba/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/sync v0.0.0-20181108010431-42b317875d0f h1:Bl/8QSvNqXvPGPGXa2z5xUTmV7VDcZyvRZ+QQXkXTZQ=
 golang.org/x/sync v0.0.0-20181108010431-42b317875d0f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20190227155943-e225da77a7e6 h1:bjcUS9ztw9kFmmIxJInhon/0Is3p+EHBKNgquIzo1OI=
+golang.org/x/sync v0.0.0-20190227155943-e225da77a7e6/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20180903190138-2b024373dcd9 h1:lkiLiLBHGoH3XnqSLUIaBsilGMUjI+Uy2Xu2JLUtTas=
 golang.org/x/sys v0.0.0-20180903190138-2b024373dcd9/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a h1:1BGLXjeY4akVXGgbC9HugT3Jv3hCI0z56oJR5vAMgBU=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+google.golang.org/appengine v1.1.0/go.mod h1:EbEs0AVv82hx2wNQdGPgUI5lhzA/G0D9YwlJXL52JkM=
 google.golang.org/appengine v1.3.0 h1:FBSsiFRMz3LBeXIomRnVzrQwSDj4ibvcRexLG0LZGQk=
 google.golang.org/appengine v1.3.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=