stop usinf os.spawn (and _safe_arg where not needed)

src/zc/buildout/testing.py

@@ -111,19 +111,14 @@ def get(url):
 def _runsetup(setup, executable, *args):
     if os.path.isdir(setup):
         setup = os.path.join(setup, 'setup.py')
-    d = os.path.dirname(setup)
-
-    args = [zc.buildout.easy_install._safe_arg(arg)
-            for arg in args]
+    args = list(args)
     args.insert(0, '-q')
-    args.append(dict(os.environ, PYTHONPATH=setuptools_location))
-
     here = os.getcwd()
     try:
-        os.chdir(d)
-        os.spawnle(os.P_WAIT, executable,
-                   zc.buildout.easy_install._safe_arg(executable),
-                   setup, *args)
+        os.chdir(os.path.dirname(setup))
+        zc.buildout.easy_install.call_subprocess(
+            [executable, setup] + args,
+            env=dict(os.environ, PYTHONPATH=setuptools_location))
         if os.path.exists('build'):
             rmtree('build')
     finally:

src/zc/buildout/tests.py

@@ -2813,17 +2813,16 @@ def getWorkingSetWithBuildoutEgg(test):
         # We have a develop egg, create a real egg for it:
         here = os.getcwd()
         os.chdir(os.path.dirname(dist.location))
-        assert os.spawnle(
-            os.P_WAIT, sys.executable,
-            zc.buildout.easy_install._safe_arg(sys.executable),
+        zc.buildout.easy_install.call_subprocess(
+            [sys.executable,
              os.path.join(os.path.dirname(dist.location), 'setup.py'),
-            '-q', 'bdist_egg', '-d', eggs,
-            dict(os.environ,
+             '-q', 'bdist_egg', '-d', eggs],
+            env=dict(os.environ,
                      PYTHONPATH=pkg_resources.working_set.find(
                          pkg_resources.Requirement.parse('setuptools')
                          ).location,
                      ),
-            ) == 0
+            )
         os.chdir(here)
         os.remove(os.path.join(eggs, 'zc.buildout.egg-link'))