tests: mark test-check-pyflakes.t as requiring hg1.0+

hg does not yet run with py3, so if you try:
./run-tests.py --local test-check-pyflakes.t

... it will try to run the local hg, which does not work
and thus, hg locate will return no output to stdout (and
stderr is sent to /dev/null).

If you do:
./run-tests.py --with-hg=~/bin/hg test-check-pyflakes.t
Then it should work, if your hg is new enough to have
a locate command (hg0.6 does not have locate).

tests/test-check-pyflakes.t

@@ -1,4 +1,4 b''
-#require test-repo pyflakes
+#require test-repo pyflakes hg10
 
   $ cd "`dirname "$TESTDIR"`"