run-tests: ensure install directories exist

As part of the transition to setuptools, it was discovered that
setuptools doesn't create install directories for you where distutils
apparently did. This was causing run-tests.py to fail when creating the
temporary hg install.

We work around this problem by creating the install directories before
running setup.py.

tests/run-tests.py

@@ -1863,6 +1863,17 b' class TestRunner(object):'
                   'prefix': self._installdir, 'libdir': self._pythondir,
                   'bindir': self._bindir,
                   'nohome': nohome, 'logfile': installerrs})
+
+        # setuptools requires install directories to exist.
+        def makedirs(p):
+            try:
+                os.makedirs(p)
+            except OSError, e:
+                if e.errno != errno.EEXIST:
+                    raise
+        makedirs(self._pythondir)
+        makedirs(self._bindir)
+
         vlog("# Running", cmd)
         if os.system(cmd) == 0:
             if not self.options.verbose: