Move GEM_PATH part of rubygems' setup hook to ruby

Fixes #1413

Signed-off-by: Shea Levy <shea@shealevy.com>

pkgs/development/interpreters/ruby/ruby-18.nix

@@ -33,8 +33,19 @@ stdenv.mkDerivation rec {
   configureFlags = ["--enable-shared" "--enable-pthread"];
 
   installFlags = stdenv.lib.optionalString docSupport "install-doc";
+
+  postInstall = ''
     # Bundler tries to create this directory
-  postInstall = "mkdir -pv $out/${passthru.gemPath}";
+    mkdir -pv $out/${passthru.gemPath}
+    mkdir -p $out/nix-support
+    cat > $out/nix-support/setup-hook <<EOF
+    addGemPath() {
+      addToSearchPath GEM_PATH \$1/${passthru.gemPath}
+    }
+
+    envHooks+=(addGemPath)
+    EOF
+  '';
 
   meta = {
     license = "Ruby";

pkgs/development/interpreters/ruby/ruby-19.nix

@@ -48,8 +48,19 @@ stdenv.mkDerivation rec {
     ++ ( if stdenv.isDarwin then [ "--with-out-ext=tk " ] else [ ]);
 
   installFlags = stdenv.lib.optionalString docSupport "install-doc";
+
+  postInstall = ''
     # Bundler tries to create this directory
-  postInstall = "mkdir -pv $out/${passthru.gemPath}";
+    mkdir -pv $out/${passthru.gemPath}
+    mkdir -p $out/nix-support
+    cat > $out/nix-support/setup-hook <<EOF
+    addGemPath() {
+      addToSearchPath GEM_PATH \$1/${passthru.gemPath}
+    }
+
+    envHooks+=(addGemPath)
+    EOF
+  '';
 
   meta = {
     license     = "Ruby";

pkgs/development/interpreters/ruby/ruby-2.0.nix

@@ -46,7 +46,18 @@ stdenv.mkDerivation rec {
 
   installFlags = stdenv.lib.optionalString docSupport "install-doc";
   # Bundler tries to create this directory
-  postInstall = "mkdir -pv $out/${passthru.gemPath}";
+  postInstall = ''
+    # Bundler tries to create this directory
+    mkdir -pv $out/${passthru.gemPath}
+    mkdir -p $out/nix-support
+    cat > $out/nix-support/setup-hook <<EOF
+    addGemPath() {
+      addToSearchPath GEM_PATH \$1/${passthru.gemPath}
+    }
+
+    envHooks+=(addGemPath)
+    EOF
+  '';
 
   meta = {
     license = "Ruby";

pkgs/development/interpreters/ruby/rubygems.nix

@@ -18,12 +18,6 @@ rec {
     cat > $out/nix-support/setup-hook <<EOF
     export RUBYOPT=rubygems
     addToSearchPath RUBYLIB $out/lib
-
-    addGemPath() {
-      addToSearchPath GEM_PATH \$1/${ruby.gemPath}
-    }
-
-    envHooks+=(addGemPath)
     EOF'') ["minInit" "addInputs" "doUnpack" "defEnsureDir"];
 
   /* doConfigure should be specified separately */