buildout.dumppickedversions doesn't print the list of picked versions if an output file is given. I like that behavior but it's not possible with buildout 2.0.
Right now you have to set show-picked-versions = true for update-versions-file to work. (https://github.com/buildout/buildout/blob/master/src/zc/buildout/buildout.py#L999). (b.t.w. This is not documented clearly).
show-picked-versions = true
I suggest that if show-picked-versions = false but update-versions-file is set to a filename the file will get updated.
show-picked-versions = false
Good point! This is a bug. Shouldn't be too hard to fix.
Added test demonstrating #71
`update-versions-file = true` has no effect when `show-picked-versions` is
I've added a pull request #72 fixing this.
Fixed #71: when needed, write versions to file
Picked versions are stored for later printing/writing in the Installer
also when show-picked-versions is set to false but update-versions-file is set
to a file. Previously, show-picked-versions=false would also disable the versions