contrib: print the version of pytype used to do the type checking

This will help with CI.  I don't see a way to print the version of python that's
running it.  When I tried `head -n 1 $(which pytype)`, the CI run printed:

    #!/usr/bin/env bash

Locally, that gives the path to the python interpreter in the venv, so IDK
what's different.

contrib/check-pytype.sh

@@ -1,129 +1,132 b''
 #!/bin/sh
 
 set -e
 set -u
 
 cd "$(hg root)"
 
+printf "pytype version: "
+pytype --version
+
 # Many of the individual files that are excluded here confuse pytype
 # because they do a mix of Python 2 and Python 3 things
 # conditionally. There's no good way to help it out with that as far as
 # I can tell, so let's just hide those files from it for now. We should
 # endeavor to empty this list out over time, as some of these are
 # probably hiding real problems.
 #
 # hgext/absorb.py               # [attribute-error]
 # hgext/bugzilla.py             # [pyi-error], [attribute-error]
 # hgext/convert/bzr.py          # [attribute-error]
 # hgext/convert/cvs.py          # [attribute-error], [wrong-arg-types]
 # hgext/convert/cvsps.py        # [attribute-error]
 # hgext/convert/p4.py           # [wrong-arg-types] (__file: mercurial.utils.procutil._pfile -> IO)
 # hgext/convert/subversion.py   # [attribute-error], [name-error], [pyi-error]
 # hgext/fastannotate/context.py # no linelog.copyfrom()
 # hgext/fastannotate/formatter.py  # [unsupported-operands]
 # hgext/fsmonitor/__init__.py   # [name-error]
 # hgext/git/__init__.py         # [attribute-error]
 # hgext/githelp.py              # [attribute-error] [wrong-arg-types]
 # hgext/hgk.py                  # [attribute-error]
 # hgext/histedit.py             # [attribute-error], [wrong-arg-types]
 # hgext/keyword.py              # [attribute-error]
 # hgext/largefiles/storefactory.py  # [attribute-error]
 # hgext/lfs/__init__.py         # [attribute-error]
 # hgext/narrow/narrowbundle2.py # [attribute-error]
 # hgext/narrow/narrowcommands.py    # [attribute-error], [name-error]
 # hgext/rebase.py               # [attribute-error]
 # hgext/remotefilelog/basepack.py   # [attribute-error], [wrong-arg-count]
 # hgext/remotefilelog/basestore.py  # [attribute-error]
 # hgext/remotefilelog/contentstore.py   # [missing-parameter], [wrong-keyword-args], [attribute-error]
 # hgext/remotefilelog/fileserverclient.py  # [attribute-error]
 # hgext/remotefilelog/shallowbundle.py     # [attribute-error]
 # hgext/remotefilelog/remotefilectx.py  # [module-attr] (This is an actual bug)
 # hgext/sqlitestore.py          # [attribute-error]
 # hgext/zeroconf/__init__.py    # bytes vs str; tests fail on macOS
 #
 # mercurial/bundlerepo.py       # no vfs and ui attrs on bundlerepo
 # mercurial/context.py          # many [attribute-error]
 # mercurial/crecord.py          # tons of [attribute-error], [module-attr]
 # mercurial/debugcommands.py    # [wrong-arg-types]
 # mercurial/dispatch.py         # initstdio: No attribute ... on TextIO [attribute-error]
 # mercurial/exchange.py         # [attribute-error]
 # mercurial/hgweb/hgweb_mod.py  # [attribute-error], [name-error], [wrong-arg-types]
 # mercurial/hgweb/server.py     # [attribute-error], [name-error], [module-attr]
 # mercurial/hgweb/wsgicgi.py    # confused values in os.environ
 # mercurial/httppeer.py         # [attribute-error], [wrong-arg-types]
 # mercurial/interfaces          # No attribute 'capabilities' on peer [attribute-error]
 # mercurial/keepalive.py        # [attribute-error]
 # mercurial/localrepo.py        # [attribute-error]
 # mercurial/minirst.py          # [unsupported-operands], [attribute-error]
 # mercurial/pure/parsers.py     # [attribute-error]
 # mercurial/repoview.py         # [attribute-error]
 # mercurial/testing/storage.py  # tons of [attribute-error]
 # mercurial/unionrepo.py        # ui, svfs, unfiltered [attribute-error]
 # mercurial/win32.py            # [not-callable]
 # mercurial/wireprotoframing.py # [unsupported-operands], [attribute-error], [import-error]
 # mercurial/wireprotov1peer.py  # [attribute-error]
 # mercurial/wireprotov1server.py  # BUG?: BundleValueError handler accesses subclass's attrs
 
 # TODO: use --no-cache on test server?  Caching the files locally helps during
 #       development, but may be a hinderance for CI testing.
 
 # TODO: include hgext and hgext3rd
 
 pytype --keep-going --jobs auto \
     doc/check-seclevel.py hgdemandimport hgext mercurial \
     -x hgext/absorb.py \
     -x hgext/bugzilla.py \
     -x hgext/convert/bzr.py \
     -x hgext/convert/cvs.py \
     -x hgext/convert/cvsps.py \
     -x hgext/convert/p4.py \
     -x hgext/convert/subversion.py \
     -x hgext/fastannotate/context.py \
     -x hgext/fastannotate/formatter.py \
     -x hgext/fsmonitor/__init__.py \
     -x hgext/git/__init__.py \
     -x hgext/githelp.py \
     -x hgext/hgk.py \
     -x hgext/histedit.py \
     -x hgext/keyword.py \
     -x hgext/largefiles/storefactory.py \
     -x hgext/lfs/__init__.py \
     -x hgext/narrow/narrowbundle2.py \
     -x hgext/narrow/narrowcommands.py \
     -x hgext/rebase.py \
     -x hgext/remotefilelog/basepack.py \
     -x hgext/remotefilelog/basestore.py \
     -x hgext/remotefilelog/contentstore.py \
     -x hgext/remotefilelog/fileserverclient.py \
     -x hgext/remotefilelog/remotefilectx.py \
     -x hgext/remotefilelog/shallowbundle.py \
     -x hgext/sqlitestore.py \
     -x hgext/zeroconf/__init__.py \
     -x mercurial/bundlerepo.py \
     -x mercurial/context.py \
     -x mercurial/crecord.py \
     -x mercurial/debugcommands.py \
     -x mercurial/dispatch.py \
     -x mercurial/exchange.py \
     -x mercurial/hgweb/hgweb_mod.py \
     -x mercurial/hgweb/server.py \
     -x mercurial/hgweb/wsgicgi.py \
     -x mercurial/httppeer.py \
     -x mercurial/interfaces \
     -x mercurial/keepalive.py \
     -x mercurial/localrepo.py \
     -x mercurial/minirst.py \
     -x mercurial/pure/parsers.py \
     -x mercurial/repoview.py \
     -x mercurial/testing/storage.py \
     -x mercurial/thirdparty \
     -x mercurial/unionrepo.py \
     -x mercurial/win32.py \
     -x mercurial/wireprotoframing.py \
     -x mercurial/wireprotov1peer.py \
     -x mercurial/wireprotov1server.py
 
 if find .pytype/pyi -name '*.pyi' | xargs grep -ql '# Caught error'; then
     echo 'pytype crashed while generating the following type stubs:'
     find .pytype/pyi -name '*.pyi' | xargs grep -l '# Caught error' | sort
 fi