Description: ------------ We have run into this problem several times, when for whatever reason the server has run out of space. HTML_Template_Sigma creates the cache file but is unable to write data to it. On first run, the template data is loaded fine as the cache file is only created (it is left with a file size of zero) and not used. Any subsequent time the script is run however, the cache file is read, which results in HTML_Template_Sigma throwing a "Cannot find block '__global__'" exception. HTML_Template_Sigma should ignore/remove the empty cache file instead of trying to read it.

I think that rather than add a special case for cache loading, we need a more robust cache writing algorithm: 1) Cached template should be saved to a temporary file and then moved to a permanent filename; 2) An error should be raised if cache file cannot be saved or moved; Also probably: 1) Cache file should be touch()ed with mtime of original filename; 2) _isCached() should check mtimes for equality. Now if the template is replaced with an older version the cached file will not be regenerated, which is a minor WTF factor.

Fixed in Git.