I have reopened the bug #2849 several minutes ago and the
e-mail from bugzilla had the subject "[Bug 2849] New - ..."
and included the diff between the empty file and the current
bug desription (in other words it included the whole bug
description istead of only including the change I've made).
While it does make sense to include the whole bug
description in the e-mail when bug is reopened, the subject
line is obviously incorrect.
This has now been fixed in the latest changes to bugzilla.