gitlab: 12.1.6 -> 12.3.4

- Update GitLab to 12.3.4

- Update update.py to cope with the new upstream repository structure

- Refactor gitlab-shell to use buildGoPackage and bundlerEnv for
  dependencies

- Refactor gitlab-workhorse to use buildGoPackage for dependencies

- Make update.py able to update gitlab-shell and gitlab-workhorse
  dependencies

- Various fixes necessary for update to work

pkgs/applications/version-management/gitlab/gitlab-workhorse/default.nix

@@ -1,21 +1,33 @@
-{ stdenv, fetchFromGitLab, git, go }:
+{ stdenv, fetchFromGitLab, git, buildGoPackage }:
 
-stdenv.mkDerivation rec {
+buildGoPackage rec {
   pname = "gitlab-workhorse";
 
-  version = "8.7.0";
+  version = "8.10.0";
 
   src = fetchFromGitLab {
     owner = "gitlab-org";
     repo = "gitlab-workhorse";
     rev = "v${version}";
-    sha256 = "1zlngc498hnzbxwdjn3ymr0xwrnfgnzzhn9lyf37yfbjl8x28n3z";
+    sha256 = "11cfhh48dga5ghfcijb68gbx0nfr5bs3vvp2j1gam9ac37fpvk0x";
   };
 
-  buildInputs = [ git go ];
+  goPackagePath = "gitlab.com/gitlab-org/gitlab-workhorse";
+  goDeps = ./deps.nix;
+  buildInputs = [ git ];
 
   makeFlags = [ "PREFIX=$(out)" "VERSION=${version}" "GOCACHE=$(TMPDIR)/go-cache" ];
 
+  # gitlab-workhorse depends on an older version of labkit which
+  # contains old, vendored versions of some packages; gitlab-workhorse
+  # also explicitly depends on newer versions of these libraries,
+  # but buildGoPackage exposes the vendored versions instead,
+  # leading to compilation errors. Since the vendored libraries
+  # aren't used here anyway, we'll just remove them.
+  postConfigure = ''
+    rm -r "$NIX_BUILD_TOP/go/src/gitlab.com/gitlab-org/labkit/vendor"
+  '';
+
   meta = with stdenv.lib; {
     homepage = http://www.gitlab.com/;
     platforms = platforms.unix;