Include conversion: Don't try to convert an empty string.

Author: Mitten-O

dstep/translator/IncludeHandler.d

@@ -180,7 +180,8 @@ private:
     /// Checks if the given include file name should be converted to an import declaration.
     bool isConvertableInclude (string include)
     {
-        return cast(bool)(matchFirst(include, convertableIncludePattern));
+        // Do not try to convert empty strings, no matter what the pattern says.
+        return include != "" && cast(bool)(matchFirst(include, convertableIncludePattern));
     }