before:
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$ contrib/devtools/previous_release.sh -r -b v0.9.5
[...]
gzip: stdin: not in gzip format
tar: Child returned status 1
tar: Error is not recoverable: exiting now
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now:
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$ contrib/devtools/previous_release.sh -r -b v0.9.5
[...]
curl: (22) The requested URL returned error: 404 Not Found
Download failed.
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