Why the port build log file has terminal escape sequences?

[Yuri]

I redirect the log into the file: portupgrade -a 2>&1 | tee portupgrade.log
However, log still has escape sequences as if it was printed to the 
terminal:
^[[0m^[[34m^[[1mGenerating moc_mainwindow.cpp^M
^[[0m^[[34m^[[1mGenerating subscriptionlistdelegate.moc^M
^[[0m^[[34m^[[1mGenerating knconfigwidgets.moc^M
^[[0m^[[34m^[[1mGenerating previewdialog.moc^M
^[[34m^[[1mGenerating entriescountdialog.moc^M

I believe this started not long ago.
What is wrong?

Yuri