In 3b12bb225a, ":oldfiles" was taught to
behave like Vim's ":browse oldfiles" if ":oldfiles!" was used. However,
this conflates the use of ! for abandoning a modified buffer with
choosing one file out of a list of oldfiles.
Now that ":browse" is supported again, ":browse oldfiles" will allow the
user to select an old file, while still complaining if that would cause
a modified buffer to be abandoned. ":browse oldfiles!" will just
abandon the buffer, as expected.
d0c0930acf