Revert "Upgrade ERP5 code."

This reverts commit b3df1d75.

Such trick is not needed anymore, as in sanef/software.cfg uses sanef-erp5
repository clone.

software/erp5/software.cfg

@@ -52,7 +52,7 @@ location = ${buildout:parts-directory}/${:_buildout_section_name_}
 stop-on-error = true
 repository = http://git.erp5.org/repos/erp5.git
 branch = master
-command = ${git:location}/bin/git clone --quiet -b ${:branch} ${:repository} ${:location} && cd ${:location} && ${git:location}/bin/git reset --quiet --hard d478cfabce2ccdbce0a4e23a830dabcb0b9b1d80
+command = ${git:location}/bin/git clone --quiet -b ${:branch} ${:repository} ${:location} && cd ${:location} && ${git:location}/bin/git reset --quiet --hard 870235a672541b87c53e96bff7ee07d41f6d7e1f
 update-command =
 
 [versions]