Merge branch 'rp/maintenance-qol'

'git maintenance register' is taught to write configuration to an arbitrary path, and 'git for-each-repo' is taught to expand tilde characters in paths. * rp/maintenance-qol: builtin/gc.c: fix use-after-free in maintenance_unregister() maintenance --unregister: fix uninit'd data use & -Wdeclaration-after-statement maintenance: add option to register in a specific config for-each-repo: interpolate repo path arguments