nix: Add `sourcesOverrides` argument to shell.nix to set the vcs server path in jenkins.

shell.nix

@@ -1,81 +1,83 b''
 { pkgs ? (import <nixpkgs> {})
 , pythonPackages ? "python27Packages"
 , doCheck ? true
+, sourcesOverrides ? {}
 , doDevelopInstall ? true
 }:
 
 let
-  sources = pkgs.config.rc.sources or {};
+  # Get sources from config and update them with overrides.
+  sources = (pkgs.config.rc.sources or {}) // sourcesOverrides;
 
   enterprise-ce = import ./default.nix {
     inherit pkgs pythonPackages doCheck;
   };
 
   ce-pythonPackages = enterprise-ce.pythonPackages;
 
   # This method looks up a path from `pkgs.config.rc.sources` and returns a
   # shell script which does a `python setup.py develop` installation of it. If
   # no path is found it will return an empty string.
   optionalDevelopInstall = attributeName:
     let
       path = pkgs.lib.attrByPath [attributeName] null sources;
       doIt = doDevelopInstall && path != null;
     in
       pkgs.lib.optionalString doIt (
       builtins.trace "Develop install of ${attributeName} from ${path}" ''
         echo "Develop install of '${attributeName}' from '${path}' [BEGIN]"
         pushd ${path}
         python setup.py develop --prefix $tmp_path --allow-hosts ""
         popd
         echo "Develop install of '${attributeName}' from '${path}' [DONE]"
       '');
 
   # This method looks up a path from `pkgs.config.rc.sources` and imports the
   # default.nix file if it exists. It returns the list of build inputs. If no
   # path is found it will return an empty list.
   optionalDevelopInstallBuildInputs = attributeName:
     let
       path = pkgs.lib.attrByPath [attributeName] null sources;
       nixFile = "${path}/default.nix";
       doIt = doDevelopInstall && path != null && pkgs.lib.pathExists "${nixFile}";
       derivate = import "${nixFile}" {
         inherit doCheck pkgs pythonPackages;
       };
     in
       pkgs.lib.lists.optionals doIt derivate.propagatedNativeBuildInputs;
 
   developInstalls = [ "rhodecode-vcsserver" ];
 
 in enterprise-ce.override (attrs: {
   # Avoid that we dump any sources into the store when entering the shell and
   # make development a little bit more convenient.
   src = null;
 
   buildInputs =
     attrs.buildInputs ++
     pkgs.lib.lists.concatMap optionalDevelopInstallBuildInputs developInstalls ++
     (with ce-pythonPackages; [
       bumpversion
       invoke
       ipdb
     ]);
 
   # Somewhat snappier setup of the development environment
   # TODO: think of supporting a stable path again, so that multiple shells
   #       can share it.
   preShellHook = enterprise-ce.linkNodeAndBowerPackages + ''
     # Custom prompt to distinguish from other dev envs.
     export PS1="\n\[\033[1;32m\][CE-shell:\w]$\[\033[0m\] "
 
     # Setup a temporary directory.
     tmp_path=$(mktemp -d)
     export PATH="$tmp_path/bin:$PATH"
     export PYTHONPATH="$tmp_path/${ce-pythonPackages.python.sitePackages}:$PYTHONPATH"
     mkdir -p $tmp_path/${ce-pythonPackages.python.sitePackages}
 
     # Develop installations
     python setup.py develop --prefix $tmp_path --allow-hosts ""
     echo "Additional develop installs"
   '' + pkgs.lib.strings.concatMapStrings optionalDevelopInstall developInstalls;
 
 })