autoreload hang for changed instance methods: between 7.5.0 and 7.8.0

[histed]

Possible autoreload regression in ipython 7.8.0 and jupyterlab 1.0+

With %autoreload 2, when I change a method in a source file when holding an existing instance object in memory, autoreload used to reload the changed instance code just fine. (It didn't find new methods, which required an explicit imp.reload(), but that's ok.)

With ipython 7.8.0, changing code in a method causes the kernel to hang when autoreload triggered by cell execute. Interrupting kernel gives following traceback

[autoreload of testcase failed: Traceback (most recent call last):
  File "/Users/histed/anaconda37/envs/mh37b/lib/python3.7/site-packages/IPython/extensions/autoreload.py", line 245, in check
    superreload(m, reload, self.old_objects)
  File "/Users/histed/anaconda37/envs/mh37b/lib/python3.7/site-packages/IPython/extensions/autoreload.py", line 450, in superreload
    update_generic(old_obj, new_obj)
  File "/Users/histed/anaconda37/envs/mh37b/lib/python3.7/site-packages/IPython/extensions/autoreload.py", line 387, in update_generic
    update(a, b)
  File "/Users/histed/anaconda37/envs/mh37b/lib/python3.7/site-packages/IPython/extensions/autoreload.py", line 357, in update_class
    update_instances(old, new)
  File "/Users/histed/anaconda37/envs/mh37b/lib/python3.7/site-packages/IPython/extensions/autoreload.py", line 312, in update_instances
    update_instances(old, new, obj.__dict__, visited)
  File "/Users/histed/anaconda37/envs/mh37b/lib/python3.7/site-packages/IPython/extensions/autoreload.py", line 317, in update_instances
    update_instances(old, new, obj, visited)
  File "/Users/histed/anaconda37/envs/mh37b/lib/python3.7/site-packages/IPython/extensions/autoreload.py", line 317, in update_instances
    update_instances(old, new, obj, visited)
  File "/Users/histed/anaconda37/envs/mh37b/lib/python3.7/site-packages/IPython/extensions/autoreload.py", line 317, in update_instances
    update_instances(old, new, obj, visited)
  File "/Users/histed/anaconda37/envs/mh37b/lib/python3.7/site-packages/IPython/extensions/autoreload.py", line 315, in update_instances
    if hasattr(obj, 'items') or (hasattr(obj, '__contains__')
KeyboardInterrupt
]

testcase.py:

class Class1:
    def __init__(self):
        print(0)

    def method(self):
        print(1)
        #print(2)

In a notebook, run:

import testcase

c = testcase.Class1()
c.method()

Then change method() by commenting/uncommenting print(2). Then run

c.method()

And kernel hangs.

[histed]

may be related to #11644 @daharn @Carreau worked on

[Naikless]

Should be solved in 7.9 or if you use the latest git version.

[histed]

confirm: latest master on github fixes this.