On #svn-dev today: [[[ <danielsh> didn't know it was valid for svn:mergeinfo properties to have an empty value
<pburba> danielsh: Yes, it allows the possibility for a subtree to inherit none of its (nearest) parent's mergeinfo. <danielsh> pburba: ie, prevent inheritance from an ancestor <pburba> danielsh: yes <danielsh> combined with a node that has no explicit mergeinfo <danielsh> pburba: thanks. (I assumed it was not an error, but thanks for confirming) <pburba> danielsh: It rarely seen in practice...well at least I've rarely seen it <danielsh> pburba: I just saw an instance of it an hour ago. <danielsh> r820355 in /repos/infra/infrastructure <danielsh> basically a copy (or replace?) with history in a setting with no mergeinfo properties at all <Bert> danielsh: I remember that some very old (1.5 / 1.6 dev) clients created that property on local copies in some situations <pburba> Bert: Yeah, I don't recall if there were some cases with URL->URL/WC copies where it still happened <danielsh> the commit was done using svn 1.7.3 ]]] So what happened here? First a little background: Since 1.5.5WC->WC copies don't record mergeinfo on the destination unless there is explicit mergeinfo on the source. This was discussed here http://svn.haxx.se/dev/archive-2008-11/0432.shtml and here http://svn.haxx.se/dev/archive-2008-11/0297.shtml However, URL->URL/WC copies still carry the inherited mergeinfo from the source and make it explicit on the target. So what happened in r820355? (Paranoia alert: Since this revision involves a private portion of the ASF repository, the actual path names and other log info in this description are fictitious. Probably overkill...) [[[ >svn log -v -r820355 ^/ ------------------------------------------------------------------------ r820355 | bob | 2011-12-06 10:42:38 -0400 (Tue, 06 Dec 2011) | 1 line Changed paths: A /infra/main/boxes/freebsd/harm8/usr/local/etc/postfix (from /infra/main/boxes/freebsd/harm8/usr/local/etc/postfix:820354) copy postfix from harm8 ]]] ^/infra/main/boxes/freebsd/harm8/usr/local/etc/postfix@820354 has no explicit mergeinfo of its own, but its parent ^/infra/main/boxes/freebsd/harm8/usr@820354 has explicit empty mergeinfo on it: [[[ >svn pg svn:mergeinfo -vR ^/infra/main/boxes/freebsd/harm8@820354 Properties on '^/infra/main/boxes/freebsd/harm8/usr': svn:mergeinfo ]]] So presumably what occurred was a URL->[URL | WC] copy, which calculated the source's inherited mergeinfo and made it explicit on the target. Now while this is expected, in this situation it is hardly ideal. Certainly cases exist where we *want* the inherited mergeinfo of the source carried to the destination (e.g. imagine ^/infra/main/boxes/freebsd/harm8 had real merge history representing merges from some third branch), but since the inherited mergeinfo of the source in this case is empty, it carries no useful information and could be safely ignored. Another case comes to mind where this behavior is unnecessary, when the soruce and destination inherit mergeinfo from the same parent. I will file an issue. -- Paul T. Burba CollabNet, Inc. -- www.collab.net -- Enterprise Cloud Development Skype: ptburba
