The crontab provider does not support crontab entries beginning with a space character although they are recognized by crond (under Debian etch but hopefully elsewhere too).
Patch available with git at ctrlaltdel/fix-for-crontab.
ctrlaltdel = http://francois.ctrlaltdel.ch/dev/puppet.git
/usr/lib/ruby/1.8/puppet/util/fileparsing.rb:240:in `parse'
/usr/lib/ruby/1.8/puppet/util/fileparsing.rb:233:in `collect'
/usr/lib/ruby/1.8/puppet/util/fileparsing.rb:233:in `parse'
/usr/lib/ruby/1.8/puppet/provider/parsedfile.rb:236:in `retrieve'
/usr/lib/ruby/1.8/puppet/provider/parsedfile.rb:201:in `prefetch_target'
/usr/lib/ruby/1.8/puppet/provider/parsedfile.rb:176:in `prefetch'
/usr/lib/ruby/1.8/puppet/provider/parsedfile.rb:175:in `each'
/usr/lib/ruby/1.8/puppet/provider/parsedfile.rb:175:in `prefetch'
/usr/lib/ruby/1.8/puppet/provider/parsedfile.rb:351:in `prefetch'
/usr/lib/ruby/1.8/puppet/metatype/evaluation.rb:21:in `evaluate'
/usr/lib/ruby/1.8/puppet/transaction.rb:58:in `apply'
/usr/lib/ruby/1.8/puppet/transaction.rb:238:in `eval_resource'
/usr/lib/ruby/1.8/puppet/util.rb:445:in `thinmark'
/usr/lib/ruby/1.8/benchmark.rb:293:in `measure'
/usr/lib/ruby/1.8/benchmark.rb:307:in `realtime'
/usr/lib/ruby/1.8/puppet/util.rb:444:in `thinmark'
/usr/lib/ruby/1.8/puppet/transaction.rb:237:in `eval_resource'
/usr/lib/ruby/1.8/puppet/transaction.rb:309:in `evaluate'
/usr/lib/ruby/1.8/puppet/util.rb:445:in `thinmark'
/usr/lib/ruby/1.8/benchmark.rb:293:in `measure'
/usr/lib/ruby/1.8/benchmark.rb:307:in `realtime'
/usr/lib/ruby/1.8/puppet/util.rb:444:in `thinmark'
/usr/lib/ruby/1.8/puppet/transaction.rb:308:in `evaluate'
/usr/lib/ruby/1.8/puppet/transaction.rb:302:in `collect'
/usr/lib/ruby/1.8/puppet/transaction.rb:302:in `evaluate'
/usr/lib/ruby/1.8/puppet/node/catalog.rb:118:in `apply'
/usr/lib/ruby/1.8/puppet/network/client/master.rb:264:in `run'
/usr/lib/ruby/1.8/puppet/util.rb:212:in `benchmark'
/usr/lib/ruby/1.8/benchmark.rb:293:in `measure'
/usr/lib/ruby/1.8/benchmark.rb:307:in `realtime'
/usr/lib/ruby/1.8/puppet/util.rb:211:in `benchmark'
/usr/lib/ruby/1.8/puppet/network/client/master.rb:263:in `run'
/usr/lib/ruby/1.8/sync.rb:229:in `synchronize'
/usr/lib/ruby/1.8/puppet/network/client/master.rb:245:in `run'
/usr/sbin/puppetd:439
err: //Node[XXXX.camptocamp.com]/base/puppet::client/Cron[mycron]: Failed to retrieve current state of resource: Could not parse line " */10\t\t * * * * /usr/bin/svn update /var/www/www.XXX.com/htdocs/sandbox" at root:4