src/Pure/Thy/thy_output.ML

   |> (if Config.get ctxt display then
         map (Pretty.indent (Config.get ctxt indent) #> string_of_margin ctxt #> Output.output)
         #> space_implode "\\isasep\\isanewline%\n"
         #> Latex.environment "isabelle"
       else
-        map ((if Config.get ctxt break then string_of_margin ctxt else Pretty.str_of) #>
-          Output.output)
+        map
+          ((if Config.get ctxt break then string_of_margin ctxt else Pretty.unformatted_string_of)
+            #> Output.output)
         #> space_implode "\\isasep\\isanewline%\n"
         #> enclose "\\isa{" "}");
 
 
 (* verbatim text *)