test/py: Use raw strings more to avoid deprecation warnings

We have two further uses of raw string usage in the test/py codebase
that are used under CI.  The first of which is under the bind test and
is a direct update.  The second of which is to strip VT100 codes from
the match buffer.  While switching this to a raw string is also a direct
update, the comment it notes that problems were encountered on Ubuntu
14.04 (and whatever Python 2 version that was) that required slight
tweaks to the regex.  Replace that now that we're saying Python 3.5 is
the minimum.

Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Stephen Warren <swarren@nvidia.com>
Tested-by: Simon Glass <sjg@chromium.org> [on sandbox]
Signed-off-by: Tom Rini <trini@konsulko.com>

test/py/tests/test_bind.py

@@ -9,11 +9,11 @@ def in_tree(response, name, uclass, drv, depth, last_child):
 	lines = [x.strip() for x in response.splitlines()]
 	leaf = ' ' * 4 * depth;
 	if not last_child:
-		leaf = leaf + '\|'
+		leaf = leaf + r'\|'
 	else:
 		leaf = leaf + '`'
 	leaf = leaf + '-- ' + name
-	line = (' *{:10.10}    [0-9]*  \[ [ +] \]   {:20.20}  {}$'
+	line = (r' *{:10.10}    [0-9]*  \[ [ +] \]   {:20.20}  {}$'
 	        .format(uclass, drv, leaf))
 	prog = re.compile(line)
 	for l in lines:

test/py/u_boot_spawn.py

@@ -42,10 +42,7 @@ class Spawn(object):
         self.after = ''
         self.timeout = None
         # http://stackoverflow.com/questions/7857352/python-regex-to-match-vt100-escape-sequences
-        # Note that re.I doesn't seem to work with this regex (or perhaps the
-        # version of Python in Ubuntu 14.04), hence the inclusion of a-z inside
-        # [] instead.
-        self.re_vt100 = re.compile('(\x1b\[|\x9b)[^@-_a-z]*[@-_a-z]|\x1b[@-_a-z]')
+        self.re_vt100 = re.compile(r'(\x1b\[|\x9b)[^@-_]*[@-_]|\x1b[@-_]', re.I)
 
         (self.pid, self.fd) = pty.fork()
         if self.pid == 0: