All in all, it is simply a matter of compliance. The doc of repr says that a repr is either

- a string that can be eval()'ed back to (an equivalent of) the original object
- or a "more loose" angle-bracket representation.

re.compile with small patterns falls in the first category. The other bug report corresponds to the second one, no problem.

However, re.compile with large patterns doesn't fall in either category, nor would it if changed to use an ellipsis.