bug#63949: 30.0.50; `vc-print-log´ does not erase buffer when called from *vc-change-log* buffer, at least for CVS logs

[Jens Schmidt]

Root cause of this issue being that `vc-deduce-fileset' does not change
buffer in Emacs 29 and newer, while it does in Emacs 27 and older.  (Too
lazy to check for Emacs 28.)

So in Emacs 27 and older, a call to `vc-print-log' started from
*vc-change-log* would change buffer to the vc parent buffer before
calling the backend function, and thus `vc-do-command' would call
`vc-setup-buffer' in the snippet mentioned above.