tests: drop some py2 specific pyflake failures

Differential Revision: https://phab.mercurial-scm.org/D12422

tests/test-check-pyflakes.t

@@ -1,28 +1,25 b''
 #require test-repo pyflakes hg10
 
   $ . "$TESTDIR/helpers-testrepo.sh"
 
 run pyflakes on all tracked files ending in .py or without a file ending
 (skipping binary file random-seed)
 
   $ cat > test.py <<EOF
   > print(undefinedname)
   > EOF
   $ "$PYTHON" -m pyflakes test.py 2>/dev/null | "$TESTDIR/filterpyflakes.py"
   test.py:1:* undefined name 'undefinedname' (glob)
   
   $ cd "`dirname "$TESTDIR"`"
 
   $ testrepohg locate 'set:**.py or grep("^#!.*python")' \
   > -X hgext/fsmonitor/pywatchman \
   > -X mercurial/pycompat.py -X contrib/python-zstandard \
   > -X mercurial/thirdparty \
   > 2>/dev/null \
   > | xargs "$PYTHON" -m pyflakes 2>/dev/null | "$TESTDIR/filterpyflakes.py"
   contrib/perf.py:*:* undefined name 'xrange' (glob) (?)
   mercurial/hgweb/server.py:*:* undefined name 'reload' (glob) (?)
-  mercurial/util.py:*:* undefined name 'file' (glob) (?)
-  mercurial/encoding.py:*:* undefined name 'localstr' (glob) (?)
-  tests/run-tests.py:*:* undefined name 'PermissionError' (glob) (?)
   mercurial/util.py:*:* 'pickle' imported but unused (glob)