contrib: Add explanatory comment to tc.sh #21289

I added a comment which would have saved me a lot of time if it's accurate. Is it?

tc.sh is used to limit bandwidth. I ran it and it is limiting my bandwidth. When I ran it, I got one error. I have not found an explanation anywhere of what the error means, but my best guess is consistent with the result, so I propose the explanatory comment to save others time when they use it and also get the error. A better fix is for tc NOT to report the failure to delete a qdisc when it's a result of there being no such qdisc. I'll go look for a tc maintainer now to see if it can be changed to a warning.

Please change your commit message to something like "contrib: Add explanatory comment to tc.sh". Looks good to me otherwise.

Please change your commit message to something like "contrib: Add explanatory comment to tc.sh". Looks good to me otherwise.

I didn't think you could change a commit message, so I made a new commit with the message you suggested, and surrounded the tc output with single quotes so the sentence I wrote is clearer.

Please squash your commits according to https://github.com/bitcoin/bitcoin/blob/master/CONTRIBUTING.md#squashing-commits

I didn't think you could change a commit message

For next time: git commit --amend then git push -f is the fastest way to do so if you have only one commit.

Now that you already created a second commit you'll have to follow the squashing (rebase) instructions that @MarcoFalke refers to.

I discovered that my fork is behind by several thousand commits and bringing it up to date required resolving conflicts so I deleted it. Now I'm starting over. I will open a new PR with a good title and a good commit message. You proposed "contrib: ..." but that is not a prefix listed in the CONTRIBUTING doc which I just finally (sorry) read. As @fanquake tagged it, I will use "script: Add explanatory comment to tc.sh"

In future, please don't open new PRs for the same change.