Set PYTHONIOENCODING before running tests

* tests/spec/check-spec: Set PYTHONIOENCODING to 'utf-8' before
running tests.

tests/spec/check-spec

@@ -7,4 +7,12 @@ test_name=$(basename "$1")
 test_name=${test_name%.sh}
 test_name=${test_name%.test}
 
+# This just makes sure that Python 2 produces UTF-8 output when
+# redirected to a file (as in the case of our test harness).  There is
+# a specific issue that this resolves.  Guile sometimes prints
+# ellipses as part of its stack traces.  If Python 2 thinks that it
+# should only write ASCII to files, it will throw an error when it
+# sees an ellipsis.
+export PYTHONIOENCODING=utf-8
+
 ./test/spec.sh "$test_name" --verbose