Support --no-listeners in loadpaths

lib/mix/lib/mix/tasks/deps.loadpaths.ex

@@ -23,6 +23,7 @@ defmodule Mix.Tasks.Deps.Loadpaths do
     * `--no-compile` - does not compile even if files require compilation
     * `--no-deps-check` - does not check or compile deps, only load available ones
     * `--no-elixir-version-check` - does not check Elixir version
+    * `--no-listeners` - does not start Mix listeners
     * `--no-optional-deps` - does not compile or load optional deps
 
   """
@@ -71,7 +72,9 @@ defmodule Mix.Tasks.Deps.Loadpaths do
 
     # For now we only allow listeners defined in dependencies, so
     # we start them right after adding adding deps to the path
-    Mix.PubSub.start_listeners()
+    if "--no-listeners" not in args do
+      Mix.PubSub.start_listeners()
+    end
 
     :ok
   end

lib/mix/lib/mix/tasks/loadpaths.ex

@@ -21,6 +21,7 @@ defmodule Mix.Tasks.Loadpaths do
     * `--no-compile` - does not compile dependencies, only check and load them
     * `--no-deps-check` - does not check dependencies, only load available ones
     * `--no-elixir-version-check` - does not check Elixir version
+    * `--no-listeners` - does not start Mix listeners
     * `--no-optional-deps` - does not compile or load optional deps
 
   """

lib/mix/test/mix/tasks/compile_test.exs

@@ -389,6 +389,10 @@ defmodule Mix.Tasks.CompileTest do
       File.write!("src/b.erl", "-module(b).")
       File.write!("src/c.erl", "-module(c).")
 
+      # Ensure we can boot with compilation and listeners if desired
+      assert mix(["loadpaths", "--no-compile", "--no-listeners"]) == ""
+
+      # Now setup dependencies
       mix(["deps.compile"])
 
       parent = self()