PR libstdc++/78389
* include/bits/list.tcc (merge(list&&)):
Adjust list sizes if the comparator throws.
(merge(list&&, _StrictWeakOrdering)): Likewise.
(sort()): Splice elements back from the scratch buffers
if the comparator throws.
(sort(_StrictWeakOrdering)): Likewise.
* testsuite/23_containers/list/operations/78389.cc: New.

From-SVN: r244439