[PY 3.8] test fixes for file closings, rawstrings

On a linux host (missing some things that may be on the Travis CI
setup), Py3.8a3 now shows 19 fails, 1048 pass, with 84 Warning: messages.

Signed-off-by: Mats Wichmann <mats@linux.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/test/Subst/null-sources-attr.py b/test/Subst/null-sources-attr.py
index 64a0b5b..729aa99 100644
--- a/test/Subst/null-sources-attr.py
+++ b/test/Subst/null-sources-attr.py
@@ -37,10 +37,10 @@ test = TestSCons.TestSCons()
 
 test.write('cat.py', """\
 import sys
-fp = open(sys.argv[1], 'wb')
-for infile in sys.argv[2:]:
-  fp.write(open(infile, 'rb').read())
-fp.close()
+with open(sys.argv[1], 'wb') as ofp:
+    for infile in sys.argv[2:]:
+      with open(infile, 'rb') as ifp:
+          ofp.write(ifp.read())
 sys.exit(0)
 """)