Merge branch 'jk/reading-packed-refs'

An earlier rewrite to use strbuf_getwholeline() instead of fgets(3) to read packed-refs file revealed that the former is unacceptably inefficient. * jk/reading-packed-refs: t1430: add another refs-escape test read_packed_refs: avoid double-checking sane refs strbuf_getwholeline: use getdelim if it is available strbuf_getwholeline: avoid calling strbuf_grow strbuf_addch: avoid calling strbuf_grow config: use getc_unlocked when reading from file strbuf_getwholeline: use getc_unlocked git-compat-util: add fallbacks for unlocked stdio strbuf_getwholeline: use getc macro