GUI
fossil ui
で立ち上げたブラウザの設定から、ignore-glob に設定する。
CUI
fossil settings ignore-glob "*/log.txt"
ignore-glob の説明文
The VALUE is a comma or newline-separated list of GLOB patterns specifying files that the "add", "addremove", "clean", and "extra" commands will ignore.
Example: *.log customCode.c notes.txt