Merge branch 'jk/commit-author-parsing'

Code clean-up.

* jk/commit-author-parsing:
determine_author_info(): copy getenv output
determine_author_info(): reuse parsing functions
date: use strbufs in date-formatting functions
record_author_date(): use find_commit_header()
record_author_date(): fix memory leak on malformed commit
commit: provide a function to find a header in a buffer

diff --cc builtin/commit.c
Simple merge

diff --cc cache.h
Simple merge

diff --cc commit.h
Simple merge

diff --cc date.c
Simple merge

diff --cc fast-import.c
Simple merge

diff --cc ident.c
Simple merge

diff --cc pretty.c
Simple merge