* which is interpreted as how many revision back from the current
* one do we want. rev=0 is reserved for the last (committed) revision.
* We need rev to be string, since in various VCS revision is not integer.
+ * If RCS addressed by a single number, it is automatically used
+ * as the last number in the whole revision specification (it applies
+ * for retrieving normal revisions (rev>0) or backtracking (rev<0).
*/
bool prepareFileRevision(std::string const & rev, std::string & f);
/// Does the current VC supports this operation?