#10458 improves cut & paste of doctest code & output from an actual Sage session, in that it allows also "....: " for line continuations. (Previously, for some reason only "..." was supported in docstrings; also the confusion with an ellipsis intended to mean arbitrary output should be reduced by this ticket.)
Another problem still has to be addressed: The original (non-preparsed) source code of continuation lines gets "lost", i.e. doesn't end up in the end-of-line comments of the generated test files (.doctest_*) as it does for ordinary lines, hence also won't be shown on doctest errors or when one doctests in verbose mode.
