Set rebar.config "lib_dirs" to the built CouchDB location

lib/templates/rebar.config.script

@@ -0,0 +1,27 @@
+Add = fun(Dirs, Dir) -> ok
+  , case lists:member(Dir, Dirs)
+    of true -> Dirs
+    ; _     -> Dirs ++ [Dir]
+    end
+  end
+.
+
+case os:getenv("COUCHDB_DEP")
+  of false -> CONFIG % env var not defined
+  ; ""     -> CONFIG % env var set to empty string
+  ; Dir -> ok
+    % Always replace the library path given. This guarantees the most isolation and portability of the plugin. However, it may
+    % make things brittle.
+    , Dirs = case lists:keyfind(lib_dirs, 1, CONFIG)
+      of false -> ok
+        , []
+      ; {lib_dirs, Lib_dirs} -> ok
+        %, Lib_dirs % Nope
+        , []
+      end
+    , New_dirs = Add(Dirs, Dir)
+    , Result = lists:keystore(lib_dirs, 1, CONFIG, {lib_dirs, New_dirs})
+    , io:format(standard_error, "Rebar config:\n~p\n", [Result])
+    , Result
+  end
+.

tasks/couchdb.rake

@@ -147,13 +147,23 @@ namespace :couchdb do
           gmake "COUCH_SRC='#{COUCH_SOURCE}/src/couchdb' clean"
           gmake "COUCH_SRC='#{COUCH_SOURCE}/src/couchdb'"
         elsif File.exists? 'rebar'
+          make_script = false
           begin
-            ENV['ERL_COMPILER_OPTIONS'] = "[{i, \"#{COUCH_SOURCE}/src/couchdb\"}]"
+            if File.exists?("rebar.config") && !File.exists?("rebar.config.script")
+              make_script = true
+              ENV['COUCHDB_DEP'] = "#{COUCH_BUILD}/lib/couchdb/erlang/lib"
+              sh "cp", "-n", "#{HERE}/lib/templates/rebar.config.script", "." # noclobber
+            else
+              ENV['ERL_COMPILER_OPTIONS'] = "[{i, \"#{COUCH_SOURCE}/src/couchdb\"}]"
+            end
+
             sh "./rebar clean"
             sh "./rebar get-deps" unless ENV['skip_deps']
             sh "./rebar compile"
           ensure
             ENV.delete('ERL_COMPILER_OPTIONS')
+            ENV.delete('COUCHDB_DEP')
+            sh "rm", "-f", "rebar.config.script" if make_script
           end
         else
           raise "I do not know how to build this plugin: #{source}"