Bug 448572
Do not log cancelled transaction exceptions in error log.

Fixed logging issues mentioned in
https://bugs.eclipse.org/bugs/show_bug.cgi?id=448572

Change-Id: Idf040bed5fb8b4552579b216d01637524b013d06
Reviewed-on: https://git.eclipse.org/r/35948
Tested-by: Hudson CI
Reviewed-by: Oli Schmid <oliver.schmid@bsiag.com>
Reviewed-on: https://git.eclipse.org/r/35949
Reviewed-by: Judith Gull <jgu@bsiag.com>