> I've just locally ran sphinx 2.0.0 on 071cbd4ea1 (the current tip of your PR) and I'm not getting any error, which one are you getting?

The issue occurs on 2347d3ae36 with `make suspicious` with Sphinx 2.0.0 and 2.0.1.

```
Doc 2347d3ae36 $ make suspicious                                                                                                                                               
mkdir -p build
Building NEWS from Misc/NEWS.d with blurb
PATH=./venv/bin:$PATH sphinx-build -b suspicious -d build/doctrees -D latex_elements.papersize=  -W . build/suspicious 
Running Sphinx v2.0.1
loading ignore rules... done, 352 rules loaded
building [mo]: targets for 0 po files that are out of date
building [suspicious]: targets for 476 source files that are out of date
updating environment: 476 added, 0 changed, 0 removed
/Users/jaraco/code/public/cpython/Doc/tools/extensions/pyspecific.py:274: RemovedInSphinx30Warning: env.note_versionchange() is deprecated. Please use ChangeSetDomain.note_changeset() instead.
  env.note_versionchange('deprecated', version[0], node, self.lineno)
reading sources... [100%] whatsnew/index                                                                                                                                       
looking for now-outdated files... none found
pickling environment... done
checking consistency... done
preparing documents... done
writing output... [ 53%] library/importlib.metadata                                                                                                                            
Exception occurred:
  File "/Users/jaraco/code/public/cpython/Doc/tools/extensions/suspicious.py", line 154, in report_issue
    self.warn('[%s:%d] "%s" found in "%-.120s"' %
AttributeError: 'CheckSuspiciousMarkupBuilder' object has no attribute 'warn'
The full traceback has been saved in /var/folders/c6/v7hnmq453xb6p2dbz1gqc6rr0000gn/T/sphinx-err-g3i65y10.log, if you want to report the issue to the developers.
Please also report this if it was a user error, so that a better error message can be provided next time.
A bug report can be filed in the tracker at <https://github.com/sphinx-doc/sphinx/issues>. Thanks!
make[1]: *** [build] Error 2
make: *** [suspicious] Error 1
Suspicious check complete; look for any errors in the above output or in build/suspicious/suspicious.csv.  If all issues are false positives, append that file to tools/susp-ignored.csv.
```