blackbox: don't unpack the list while passing into str.join() The current state may result in error TypeError. Caught using evolve-tests.

atomicupdate: add an experimental option to use atomictemp when updating In some cases Mercurial truncating files when updating causes problems. It can happens when processes are currently reading the file or with big file or on NFS mounts. We add an experimental option to use the atomictemp option of vfs.__call__ in order to avoid the problem. The localrepository.wwrite seems to assume the files are created without the `x` flag; with atomictempfile, the new file might inherit the `x` flag from the destination. We force remove it afterward. This code could be refactored and the flag processing could be moved inside vfs. This patch should be tested with `--extra-config-opt experimental.update.atomic-file=True` as we disabled the option by default. Differential Revision: https://phab.mercurial-scm.org/D1882

write: add the possibility to pass keyword argument from batchget to vfs We are going to pass atomictemp keyword argument from merge.baychget to vfs.__call__. Update all the frames to accept **kwargs and pass it to the next function. Differential Revision: https://phab.mercurial-scm.org/D1881