- restore the starting arg error back to the original intent

alembic/environment.py

@@ -179,10 +179,14 @@ class EnvironmentContext(object):
         if self._migration_context is not None:
             return self.script.as_revision_number(
                 self.get_context()._start_from_rev)
-        elif self.context_opts.get('starting_rev') is not None:
+        elif 'starting_rev' in self.context_opts:
             return self.script.as_revision_number(
                 self.context_opts['starting_rev'])
         else:
+            # this should raise only in the case that a command
+            # is being run where the "starting rev" is never applicable;
+            # this is to catch scripts which rely upon this in
+            # non-sql mode or similar
             raise util.CommandError(
                 "No starting revision argument is available.")
 

tests/test_offline_environment.py

@@ -53,14 +53,14 @@ assert context.get_starting_revision_argument() == 'x'
         command.upgrade(self.cfg, "x:y", sql=True)
         command.downgrade(self.cfg, "x:y", sql=True)
 
-    def test_starting_rev_pre_context_stamp(self):
+    def test_starting_rev_pre_context_cmd_w_no_startrev(self):
         env_file_fixture("""
 assert context.get_starting_revision_argument() == 'x'
 """)
         assert_raises_message(
             util.CommandError,
             "No starting revision argument is available.",
-            command.stamp, self.cfg, a)
+            command.current, self.cfg)
 
     def test_starting_rev_current_pre_context(self):
         env_file_fixture("""