ensure working version of setuptools_scm for python-dateutil

Install setuptools_scm before python-dateutil (which has it in setup_requires) so that the version can be controlled by buildout

See nexedi/slapos@f1e7230e

software/backupserver/software.cfg

@@ -33,7 +33,7 @@ recipe = zc.recipe.egg
 interpreter = python-${:_buildout_section_name_}
 eggs =
   PyRSS2Gen
-  python-dateutil
+  ${python-dateutil:egg}
 
 ##########################################################
 # Service startup scripts and configuration files

software/neoppod/software-common.cfg

@@ -45,6 +45,7 @@ environment = neoppod-setup-env
 [neoppod]
 recipe = zc.recipe.egg
 eggs = neoppod[admin, ctl, master]
+  ${python-dateutil:egg}
   ${cython-zstd:egg}
   ${msgpack-python:egg}
   ${:adapter-egg}

stack/slapos.cfg

@@ -126,12 +126,18 @@ eggs =
   ${pycurl:egg}
   ${python-cryptography:egg}
   ${backports.lzma:egg}
+  ${python-dateutil:egg}
 
 [jsonschema]
 recipe = zc.recipe.egg:custom
 egg = ${:_buildout_section_name_}
 setup-eggs = setuptools_scm
 
+[python-dateutil]
+recipe = zc.recipe.egg:custom
+egg = ${:_buildout_section_name_}
+setup-eggs = setuptools_scm
+
 # Install a slapos command with networkcache enabled in ${buildout:bin-directory}
 [slapos-command]
 recipe = zc.recipe.egg