Clarify precedence for template/style in commands.show_changeset():
Display format will be the first non-empty hit of:
1. option 'template'
2. option 'style'
3. [ui] setting 'logtemplate'
4. [ui] setting 'style'
If all of these values are either the unset or the empty string,
regular display via changeset_printer() is done.
abort: edit failed: false exited with status 1
transaction abort!
rollback completed
abort: edit failed: false exited with status 1
transaction abort!
rollback completed