Please change source:trunk/app/models/changeset.rb#L144
from
@to_utf8(str.to_s.strip)@
to
@to_utf8(str.to_s)@

The wiki formatting used by Trac requires that bullet lists include a leading space before the asterisk. The wiki formatter used in Redmine appears to accept the bullet list syntax with and without the leading space, but not a mixture of both.

When importing a subversion repository which was used with Trac, it is important to preserve this leading space, otherwise the changeset comment is formatted by Redmine as one bullet entry containing multiple asterisks.

Perhaps an example will help:
the changeset message is

 * item 1
 * item 2
 * item 3

which when stripped is inserted in the database as:

* item 1
 * item 2
 * item 3

causing Redmine to format it as:

• item 1
  • item 2
  • item 3