Install pyrsistent with setup-eggs

This repairs buildout profiles on python 2.

To backport the patch on old profiles, a simpler version is to append this to buildout.cfg :

```
[versions]
pyrsistent = 0.16.1
```

See merge request !908

software/erp5/upgrade_test/test.py

@@ -39,7 +39,7 @@ from slapos.testing.testcase import installSoftwareUrlList
 from slapos.testing.testcase import SlapOSNodeCommandError
 from slapos.grid.utils import md5digest
 
-old_software_release_url = 'https://lab.nexedi.com/nexedi/slapos/raw/1.0.167/software/erp5/software.cfg'
+old_software_release_url = 'https://lab.nexedi.com/nexedi/slapos/raw/1.0.167.1/software/erp5/software.cfg'
 new_software_release_url = os.path.abspath(
     os.path.join(os.path.dirname(__file__), '..', 'software.cfg'))
 

software/kvm/software.cfg

@@ -50,7 +50,7 @@ eggs =
   ${python-cffi:egg}
   ${lxml-python:egg}
   websockify
-  slapos.cookbook
+  ${slapos-cookbook:eggs}
   erp5.util
 # BBB: eggs used as recipe should be kept otherwise sections depending
 # on it can't be uninstalled

stack/slapos.cfg

@@ -92,6 +92,11 @@ recipe = zc.recipe.egg
 eggs = slapos.cookbook
 depends = ${slapos-cookbook-dependencies:eggs}
 
+[pyrsistent]
+recipe = zc.recipe.egg:custom
+egg = pyrsistent
+setup-eggs = pytest-runner
+
 [slapos-cookbook-dependencies]
 recipe = zc.recipe.egg
 eggs =
@@ -101,6 +106,7 @@ eggs =
   ${python-cachecontrol:egg}
   ${python-cliff:egg}
   ${python-cryptography:egg}
+  ${pyrsistent:egg}
   ${jsonschema:egg}
 
 # slapos.toolbox containing utilities
@@ -262,18 +268,28 @@ erp5.util = 0.4.69
 feedparser = 5.2.1
 
 # Required by:
-# jsonschema==2.6.0
+# jsonschema==3.0.2
 functools32 = 3.2.3.post2
 
 # Required by:
-# jsonschema==2.6.0
+# jsonschema==3.0.2
+attrs = 18.2.0
+
+# Required by:
+# jsonschema==3.0.2
+pyrsistent = 0.16.1
+
+pytest-runner = 5.2.0
+
+# Required by:
+# jsonschema==3.0.2
 setuptools-scm = 3.5.0
 
 ipaddress = 1.0.23
 
 # Required by:
 # slapos.cookbook==1.0.143
-jsonschema = 2.6.0
+jsonschema = 3.0.2
 
 # Required by:
 # slapos.toolbox==0.94