THRIFT-3910 Do not invoke pip as part of build process

This closes #1073
diff --git a/test/Makefile.am b/test/Makefile.am
index fb39a12..1a1bf47 100755
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -53,8 +53,10 @@
 if WITH_PYTHON
 SUBDIRS += py
 PRECROSS_TARGET += precross-py
-SUBDIRS += py.twisted
 SUBDIRS += py.tornado
+if WITH_TWISTED_TEST
+SUBDIRS += py.twisted
+endif
 endif
 
 if WITH_RUBY