notebook: total=None display improvements

- fixes #1015
- also fix potential `kwarg` override issue

tqdm/notebook.py

@@ -103,6 +103,8 @@ def status_printer(_, total=None, desc=None, ncols=None):
             pbar = IProgress(min=0, max=1)
             pbar.value = 1
             pbar.bar_style = 'info'
+            if ncols is None:
+                pbar.layout.width = "20px"
 
         if desc:
             pbar.description = desc
@@ -129,6 +131,13 @@ def status_printer(_, total=None, desc=None, ncols=None):
 
         return container
 
+    @staticmethod
+    def format_meter(n, total, *args, **kwargs):
+        if total and 'bar_format' not in kwargs:
+            kwargs = kwargs.copy()
+            kwargs['bar_format'] = "{l_bar}<bar/>{r_bar}"
+        return std_tqdm.format_meter(n, total, *args, **kwargs)
+
     def display(self, msg=None, pos=None,
                 # additional signals
                 close=False, bar_style=None):
@@ -182,15 +191,17 @@ def display(self, msg=None, pos=None,
                 self.container.visible = False
 
     def __init__(self, *args, **kwargs):
+        kwargs = kwargs.copy()
         # Setup default output
         file_kwarg = kwargs.get('file', sys.stderr)
         if file_kwarg is sys.stderr or file_kwarg is None:
             kwargs['file'] = sys.stdout  # avoid the red block in IPython
 
         # Initialize parent class + avoid printing by using gui=True
         kwargs['gui'] = True
-        kwargs.setdefault('bar_format', '{l_bar}{bar}{r_bar}')
-        kwargs['bar_format'] = kwargs['bar_format'].replace('{bar}', '<bar/>')
+        if 'bar_format' in kwargs:
+            kwargs['bar_format'] = kwargs['bar_format'].replace(
+                '{bar}', '<bar/>')
         # convert disable = None to False
         kwargs['disable'] = bool(kwargs.get('disable', False))
         super(tqdm_notebook, self).__init__(*args, **kwargs)