Mark directory "py2only" as source root in both IDEA module and PyCharm project

I didn't mark "py3only" though, because it might lead to resolution ambiguities
and normally we use Python 2 to write and test helper scripts.

python/helpers/.idea/helpers.iml

@@ -3,6 +3,7 @@
   <component name="NewModuleRootManager">
     <content url="file://$MODULE_DIR$">
       <sourceFolder url="file://$MODULE_DIR$/pydev" isTestSource="false" />
+      <sourceFolder url="file://$MODULE_DIR$/py2only" isTestSource="false" />
     </content>
     <orderEntry type="jdk" jdkName="PyCharm Python SDK" jdkType="Python SDK" />
     <orderEntry type="sourceFolder" forTests="false" />

python/python-helpers.iml

@@ -3,11 +3,11 @@
   <component name="NewModuleRootManager" inherit-compiler-output="true">
     <exclude-output />
     <content url="file://$MODULE_DIR$/helpers">
+      <sourceFolder url="file://$MODULE_DIR$/helpers/py2only" isTestSource="false" />
       <sourceFolder url="file://$MODULE_DIR$/helpers" isTestSource="false" />
     </content>
     <orderEntry type="inheritedJdk" />
     <orderEntry type="sourceFolder" forTests="false" />
     <orderEntry type="module" module-name="util" />
   </component>
-</module>
-
+</module>