tests: Teach to run with ZEO5

Since 7fc4ec66 (tests: Allow to test with ZEO & NEO ZODB storages) we
can run the tests with either FileStorage, ZEO or NEO. But ZEO test
adapter started to fail with ZEO5:

	self = <wendelin.lib.testing.TestDB_ZEO object at 0x7f1feb5091d0>

	    def setup(self):
	        port  = self.zeo_forker.get_port()
	        zconf = self.zeo_forker.ZEOConfig(('', port))
	        self.addr, self.adminaddr, self.pid, self.path = \
	>               self.zeo_forker.start_zeo_server(zeo_conf=zconf, port=port)
	E       ValueError: need more than 2 values to unpack

This is because in ZEO5 forker.start_zeo_server() was reworked to return only
addr and stop closure instead of returning all details and relying on caller to
implement stop itself.

Adapt the test to detect ZEO5 and use new calling convention.

lib/testing.py

@@ -27,6 +27,7 @@ from ZODB import DB
 import codecs
 import math
 import os
+import pkg_resources
 
 # hashlib-like interface to adler32
 class Adler32:
@@ -211,13 +212,32 @@ class TestDB_ZEO(TestDB_Base):
         from ZEO.tests import forker
         self.zeo_forker = forker
 
+        # .z5 represents whether we are running with ZEO5 or earlier
+        dzodb3  = pkg_resources.working_set.find(pkg_resources.Requirement.parse('ZODB3'))
+        dzeo    = pkg_resources.working_set.find(pkg_resources.Requirement.parse('ZEO'))
+        v5      = pkg_resources.parse_version('5.0dev')
+        v311    = pkg_resources.parse_version('3.11dev')
+
+        if dzodb3 is not None and dzodb3.parsed_version < v311:
+            self.z5 = False # ZODB 3.11 just requires latest ZODB & ZEO
+        else:
+            assert dzeo is not None
+            self.z5 = (dzeo.parsed_version >= v5)
+
+
     def setup(self):
         port  = self.zeo_forker.get_port()
         zconf = self.zeo_forker.ZEOConfig(('', port))
-        self.addr, self.adminaddr, self.pid, self.path = \
-                self.zeo_forker.start_zeo_server(zeo_conf=zconf, port=port)
+        _ = self.zeo_forker.start_zeo_server(zeo_conf=zconf, port=port)
+        if self.z5:
+            self.addr, self.stop = _
+        else:
+            self.addr, self.adminaddr, self.pid, self.path = _
 
     def teardown(self):
+        if self.z5:
+            self.stop()
+        else:
             self.zeo_forker.shutdown_zeo_server(self.adminaddr)
             os.waitpid(self.pid, 0)