checknlink: use a random temp file name for checking Previously, if `.hg/store/00manifest.d.hgtmp1` exists, hg will copy the entire `00manifest.d` every time when appending new manifest revisions. That could happen if Mercurial or the machine crashed when `.hgtmp1` was just created but not deleted yet. This patch changes the fixed name to a random generated name. To be consistent with D468, `~` suffix was used. Differential Revision: https://phab.mercurial-scm.org/D611