Merge branch 'js/fetch-multi-lockfix'

Fetching from multiple remotes into the same repository in parallel had a bad interaction with the recent change to (optionally) update the commit-graph after a fetch job finishes, as these parallel fetches compete with each other. Which has been corrected. * js/fetch-multi-lockfix: fetch: avoid locking issues between fetch.jobs/fetch.writeCommitGraph fetch: add the command-line option `--write-commit-graph`