tests: don't need separate module for id_allocation_test any more

This used to be because everything would explode while importing
__main__ under py.test, but that was fixed months ago.

tests/data/id_allocation.py

@@ -1,10 +0,0 @@
-
-import mitogen.core
-import mitogen.parent
-
-
-@mitogen.core.takes_econtext
-def allocate_an_id(econtext):
-    mitogen.parent.upgrade_router(econtext)
-    return econtext.router.allocate_id()
-

tests/id_allocation_test.py

@@ -2,7 +2,15 @@
 import unittest2
 
 import testlib
-import id_allocation
+
+import mitogen.core
+import mitogen.parent
+
+
+@mitogen.core.takes_econtext
+def allocate_an_id(econtext):
+    mitogen.parent.upgrade_router(econtext)
+    return econtext.router.allocate_id()
 
 
 class SlaveTest(testlib.RouterMixin, testlib.TestCase):
@@ -12,11 +20,11 @@ class SlaveTest(testlib.RouterMixin, testlib.TestCase):
         self.assertEquals(1, context.context_id)
 
         # First call from slave allocates a block (2..1001)
-        id_ = context.call(id_allocation.allocate_an_id)
+        id_ = context.call(allocate_an_id)
         self.assertEqual(id_, 2)
 
         # Second call from slave allocates from block (3..1001)
-        id_ = context.call(id_allocation.allocate_an_id)
+        id_ = context.call(allocate_an_id)
         self.assertEqual(id_, 3)
 
         # Subsequent master allocation does not collide