[Backport to release/v1.1] Internal: Fix reader reordering in FlowSynchronizationGroup::waitForDataAt - #713
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…ataAt std::forward_list::splice_after(pos, other, it) moves the element *following* `it`, not `*it`. waitForDataAt passed the iterator of the entry it wanted to promote, so it moved that entry's successor instead, and when the entry to promote was the last one in the list, `std::next(it)` was the end iterator and the call was undefined behaviour. In practice the list ends up empty, and every subsequent call iterates over nothing and returns MXL_STATUS_OK immediately: the group silently stops synchronizing after its first reordering, which is a failure that looks like success. A single-member group never reaches that branch, since the guard requires an entry whose observed source delay exceeds the head's, so only groups with two or more readers are affected. Pass the predecessor of the entry to be promoted, and keep track of it while walking the list. Signed-off-by: rochonma <mathieu.rochon@radio-canada.ca> (cherry picked from commit f0fff0c)
Signed-off-by: rochonma <mathieu.rochon@radio-canada.ca> (cherry picked from commit 26ceaf0)
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Backport of #711 to
release/v1.1.