windows: add win32com.shell to demandimport ignore list

Module 'appdirs' tries to import win32com.shell (and catch ImportError as an
indication of failure) to check whether some further functionality should
be implemented one or another way [1]. Of course, demandimport lets it down, so
if we want appdirs to work we have to add it to demandimport's ignore list.

The reason we want appdirs to work is becuase it is used by setuptools [2] to
determine egg cache location. Only fairly recent versions of setuptools depend
on this so people don't see this often.


[1] https://github.com/ActiveState/appdirs/blob/master/appdirs.py#L560
[2] https://github.com/pypa/setuptools/blob/aae0a928119d2a178882c32bded02270e30d0273/pkg_resources/__init__.py#L1369

mercurial/demandimport.py

@@ -274,6 +274,7 b' ignore = ['
     'fcntl',
     'nt', # pathlib2 tests the existence of built-in 'nt' module
     'win32com.gen_py',
+    'win32com.shell', # 'appdirs' tries to import win32com.shell
     '_winreg', # 2.7 mimetypes needs immediate ImportError
     'pythoncom',
     # imported by tarfile, not available under Windows

tests/test-check-code.t

@@ -13,7 +13,7 b' New errors are not allowed. Warnings are'
    >             r.revision(r.node(x))
    don't convert rev to node before passing to revision(nodeorrev)
   Skipping i18n/polib.py it has no-che?k-code (glob)
-  mercurial/demandimport.py:312:
+  mercurial/demandimport.py:313:
    >     if os.environ.get('HGDEMANDIMPORT') != 'disable':
    use encoding.environ instead (py3)
   mercurial/encoding.py:54: