various issues with filtering commits from log

moin!

i have to deal with a repo which has relatively little traffic, except that a bot is constantly spamming it, making it basically unfeasible to get a quick overview of what happened.

so i thought, "there certainly is an --exclude-author option, and ideally, i can persist it in the config as the default". well, no. what i got is "--perl-regexp --author='^(?!The Bot)'". that's .. not user friendly.

once i got there, i noticed that --graph tears apart the history. the manual talks about parent rewriting, but clearly this is not applied to _this_ kind of history simplification.

so next i tried to approximate the desired result by logging only the most interesting subdirectory, which the bot luckily doesn't touch. this actually looks kinda reasonable, with the catch that a lot of tags & branches are missing from the decorations. this of course makes sense, as the relevant commits are not listed. however, it would be rather desirable to have parent rewriting be applied here as well, so "fake" decorations would be shown (with an indication where this was done).

these issues affect "log --all" particularly strongly, as it's not really clear what belongs where.

somewhat unsurprisingly, these issues also affect gitk.