XUnit Formatter: Handle UTF-8 decode errors on invalid XML

Strings which contain garbage data can trigger an exception in the XUnit
plugin at the UTF-8 decode step because the decode is strict. Use a lax
mode to avoid an exception.

See: https://ci.swift.org/job/oss-lldb-incremental-osx/780
llvm-svn: 323817

lldb/packages/Python/lldbsuite/test_event/formatter/xunit.py

@@ -84,7 +84,9 @@ class XunitFormatter(ResultsFormatter):
         """
         # Get the content into unicode
         if isinstance(str_or_unicode, str):
-            unicode_content = str_or_unicode.decode('utf-8')
+            # If we hit decoding errors due to data corruption, replace the
+            # invalid characters with U+FFFD REPLACEMENT CHARACTER.
+            unicode_content = str_or_unicode.decode('utf-8', 'replace')
         else:
             unicode_content = str_or_unicode
         return self.invalid_xml_re.sub(