Work around spdx-tools assuming a "str" file instead of "unicode"

Fixes #436.

Author: sschuberth

src/scancode/cli.py

@@ -712,12 +712,20 @@ def save_results(files_count, scanned_files, format, input, output_file):
         doc.package.license_declared = NoAssert()
         doc.package.conc_lics = NoAssert()
 
+        # As the spdx-tools package can only write the document to a "str" file but ScanCode provides a "unicode" file,
+        # write to a "str" buffer first and then manually write the value to a "unicode" file.
+        from StringIO import StringIO
+
+        str_buffer = StringIO()
+
         if format == 'spdx-tv':
             from spdx.writers.tagvalue import write_document
-            write_document(doc, output_file)
+            write_document(doc, str_buffer)
         else:
             from spdx.writers.rdf import write_document
-            write_document(doc, output_file)
+            write_document(doc, str_buffer)
+
+        output_file.write(str_buffer.getvalue())
 
     else:
         raise Exception('Unknown format')