Merge branch 'js/deprecate-grafts'

Merge branch 'js/deprecate-grafts'

The functionality of "$GIT_DIR/info/grafts" has been superseded by
the "refs/replace/" mechanism for some time now, but the internal
code had support for it in many places, which has been cleaned up
in order to drop support of the "grafts" mechanism.

* js/deprecate-grafts:
  Remove obsolete script to convert grafts to replace refs
  technical/shallow: describe why shallow cannot use replace refs
  technical/shallow: stop referring to grafts
  filter-branch: stop suggesting to use grafts
  Deprecate support for .git/info/grafts
  Add a test for `git replace --convert-graft-file`
  replace: introduce --convert-graft-file
  replace: prepare create_graft() for converting graft files wholesale
  replace: "libify" create_graft() and callees
  replace: avoid using die() to indicate a bug
  commit: Let the callback of for_each_mergetag return on error
  argv_array: offer to split a string by whitespace