[JupyterLab] tqdm.auto visual output bug 4.49.0

[vfdev-5]

Visual output bug since the new 4.49.0 release with jupyter lab:

from tqdm.auto import tqdm
import tqdm as t
print(t.__version__)
import time

pbar = tqdm(
    total=None, 
    leave=False, 
    bar_format="{desc}[{n_fmt}/{total_fmt}] {percentage:3.0f}%|{bar}{postfix} [{elapsed}<{remaining}]", 
    initial=1,
    desc="Iterations"
)

for _ in range(10):
    time.sleep(0.5)
    pbar.update(1)    
    
pbar.close()

gives

When I remove bar_format visual output looks better.

• I have marked all applicable categories:
  • exception-raising bug
  • visual output bug
  • documentation request (i.e. "X is missing from the documentation." If instead I want to ask "how to use X?" I understand StackOverflow#tqdm is more appropriate)
  • new feature request
• I have visited the source website, and in particular
  read the known issues
• I have searched through the issue tracker for duplicates
• I have mentioned version numbers, operating system and
  environment, where applicable:

  import tqdm, sys
  print(tqdm.__version__, sys.version, sys.platform)

4.49.0 3.7.7 (default, Mar 23 2020, 22:36:06)
[GCC 7.3.0] linux

[casperdcl]

Can you confirm this is also the case with tqdm==4.48.2? (I think tqdm<=4.48.0 has your desired behaviour).

In all versions this should work though:

 import time

 pbar = tqdm(
-     total=None,
+     total=10,
     leave=False,
     bar_format="{desc}[{n_fmt}/{total_fmt}] {percentage:3.0f}%|{bar}{postfix} [{elapsed}<{remaining}]",

[casperdcl]

@vfdev-5 lemme know if #1032 fixes your issue.

[vfdev-5]

@casperdcl thanks for working on the issue ! Yes, you are right the behaviour I'd like is the one with tqdm<=4.48.0.

I agree that if total is set, visual output is OK.

#1032 makes the visual output same as if I use 4.49.0 and remove bar_format (in my test). Ultimately, desired visual output is like the one with tqdm<=4.48.0.