* 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