brain_mechanize provides an incomplete Browser

[pkolbus]

The mechanize.Browser provided by astroid.brain.brain_mechanize.mechanize_transform is incomplete, causing false positives E1101 / E1137 in pylint.

note: the transform itself is needed still, otherwise there are E1102 / not-callable false-positives.

Steps to reproduce

Run pylint on the following script:

import mechanize

LOGIN_URL = "https://example.com/login"
USERNAME = "my_username"
PASSWORD = "hunter2"

br = mechanize.Browser()
br.open(LOGIN_URL)
br.select_form(nr=0)
br["u"] = USERNAME
br["p"] = PASSWORD
br.submit() 

Current behavior

False positives:

E1101: Instance of 'Browser' has no 'select_form' member (no-member)
E1137: 'br' does not support item assignment (unsupported-assignment-operation)
E1101: Instance of 'Browser' has no 'submit' member (no-member)

Expected behavior

No false positives

python3 -c "from astroid import __pkginfo__; print(__pkginfo__.version)" output

2.5.0 (and reproduced with commit 3f7cea4)