Merge branch 'jk/xstrfmt'

* jk/xstrfmt: setup_git_env(): introduce git_path_from_env() helper unique_path: fix unlikely heap overflow walker_fetch: fix minor memory leak merge: use argv_array when spawning merge strategy sequencer: use argv_array_pushf setup_git_env: use git_pathdup instead of xmalloc + sprintf use xstrfmt to replace xmalloc + strcpy/strcat use xstrfmt to replace xmalloc + sprintf use xstrdup instead of xmalloc + strcpy use xstrfmt in favor of manual size calculations strbuf: add xstrfmt helper