RawHeader.get can return also string lists

Related: https://pagure.io/koji/issue/3713

koji/__init__.py

@@ -807,6 +807,14 @@ class RawHeader(object):
         elif dtype == 7:
             # raw data
             return self.header[pos:pos + count]
+        elif dtype == 8:
+            # string array
+            result = []
+            for i in range(count):
+                end = self.header.find(six.b('\0'), pos)
+                result.append(self.header[pos:end])
+                pos = end + 1
+            return result
         else:
             # XXX - not all valid data types are handled
             raise GenericError("Unable to read header data type: %x" % dtype)