use stdout for logging.INFO and lower; for the rest use stderr

docs/changelog.rst

@@ -30,12 +30,13 @@ Features
 Bug fixes
 *****************
 
-- `server_defaults` passed to :meth:`Column.create <migrate.changeset.schema.ChangesetColumn.create>` are now issued correctly
+- `server_defaults` passed to :meth:`Column.create <migrate.changeset.schema.ChangesetColumn.create>`
+  are now issued correctly
 - use SQLAlchemy quoting system to avoid name conflicts (for issue 32)
 - complete refactoring of :class:`~migrate.changeset.schema.ColumnDelta` (fixes issue 23)
 - partial refactoring of :mod:`changeset` package
 - fixed bug when :meth:`Column.alter <migrate.changeset.schema.ChangesetColumn.alter>`\(server_default='string') was not properly set
-- constraints passed to :meth:`Column.create <migrate.changeset.schema.ChangesetColumn.create>` are correctly interpreted (``ALTER TABLE ADD CONSTRAINT`` is issued after ``ATLER TABLE ADD COLUMN``)
+- constraints passed to :meth:`Column.create <migrate.changeset.schema.ChangesetColumn.create>` are correctly interpreted  (``ALTER TABLE ADD CONSTRAINT`` is issued after ``ATLER TABLE ADD COLUMN``)
 
 Documentation
 *********************

migrate/versioning/shell.py

@@ -161,12 +161,29 @@ def main(argv=None, **kwargs):
 
     # configure logging
     if not asbool(kwargs.pop('disable_logging', False)):
+        # filter to log =< INFO into stdout and rest to stderr
+        class SingleLevelFilter(logging.Filter):
+            def __init__(self, min=None, max=None):
+                self.min = min or 0
+                self.max = max or 100
+
+            def filter(self, record):
+                return self.min <= record.levelno <= self.max
+
         logger = logging.getLogger()
-        logger.setLevel(logging.INFO)
-        formatter = logging.Formatter("%(message)s")
-        ch = logging.StreamHandler(sys.stdout)
-        ch.setFormatter(formatter)
-        logger.addHandler(ch)
+        h1 = logging.StreamHandler(sys.stdout)
+        f1 = SingleLevelFilter(max=logging.INFO)
+        h1.addFilter(f1)
+        h2 = logging.StreamHandler(sys.stderr)
+        f2 = SingleLevelFilter(min=logging.WARN)
+        h2.addFilter(f2)
+        logger.addHandler(h1)
+        logger.addHandler(h2)
+
+        if options.debug:
+            logger.setLevel(logging.DEBUG)
+        else:
+            logger.setLevel(logging.INFO)
 
     log = logging.getLogger(__name__)