Merge branch 'pw/am-rebase-read-author-script'

Unify code to read the author-script used in "git am" and the
commands that use the sequencer machinery, e.g. "git rebase -i".

* pw/am-rebase-read-author-script:
  sequencer: use read_author_script()
  add read_author_script() to libgit
  am: rename read_author_script()
  am: improve author-script error reporting
  am: don't die in read_author_script()

diff --cc builtin/am.c
Simple merge

diff --cc sequencer.c
Simple merge

diff --cc sequencer.h
index 660cff5,60f15a4..5071a73
--- 1/sequencer.h
--- 2/sequencer.h
+++ b/sequencer.h
@@@ -130,8 -114,7 +130,11 @@@ int prepare_branch_to_be_rebased(struc
  #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
  void print_commit_summary(const char *prefix, const struct object_id *oid,
                          unsigned int flags);
+ 
+ int read_author_script(const char *path, char **name, char **email, char **date,
+                      int allow_missing);
  #endif
 +
 +void parse_strategy_opts(struct replay_opts *opts, char *raw_opts);
 +int write_basic_state(struct replay_opts *opts, const char *head_name,
 +                    const char *onto, const char *orig_head);