I was trapped before by using a 'logic' way to modify my bug report :
use the "edit" button available on the bug report page.
At least we could add some words in the mail that is sent when you
report a bug :
"Should you modify your report, please update it through
http://bugs.php.net/bugs.php?id=$id"
And also a warning on the bugs report page.
It seems the only difference is $edit, is it ?
Probably then, an edit = 1 should be added only if a cookie for CVS info
is detected ?
you should redirect your suggestions to zak (who´s listening of course), he wanted to step deeper into the bug system
regards,
andré