The file linked from the bug report has a meter-change
in the middle of a bar. Ardour maps this back to the previous
bar, which already has a meter-change. Session load fails with
"Multiple meter definitions found at 473"
The tempo-map of the file ends like this:
```
Meter 11/32 @227040 (beat 473)
Meter 4 / 4 @227680 (beat 483.666667)
```
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