replay: introduce new builtin

For now, this is just a rename from `t/helper/test-fast-rebase.c` into
`builtin/replay.c` with minimal changes to make it build appropriately.

Let's add a stub documentation and a stub test script though.

Subsequent commits will flesh out the capabilities of the new command
and make it a more standard regular builtin.

Helped-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Co-authored-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/Documentation/git-replay.txt b/Documentation/git-replay.txt
new file mode 100644
index 0000000000..2ca7ca5fd8
--- /dev/null
+++ b/Documentation/git-replay.txt
@@ -0,0 +1,39 @@
+git-replay(1)
+=============
+
+NAME
+----
+git-replay - EXPERIMENTAL: Replay commits on a new base, works with bare repos too
+
+
+SYNOPSIS
+--------
+[verse]
+(EXPERIMENTAL!) 'git replay' --onto <newbase> <oldbase> <branch>
+
+DESCRIPTION
+-----------
+
+Takes a range of commits, specified by <oldbase> and <branch>, and
+replays them onto a new location (see `--onto` option below).
+
+THIS COMMAND IS EXPERIMENTAL. THE BEHAVIOR MAY CHANGE.
+
+OPTIONS
+-------
+
+--onto <newbase>::
+	Starting point at which to create the new commits.  May be any
+	valid commit, and not just an existing branch name.
+
+EXIT STATUS
+-----------
+
+For a successful, non-conflicted replay, the exit status is 0.  When
+the replay has conflicts, the exit status is 1.  If the replay is not
+able to complete (or start) due to some kind of error, the exit status
+is something other than 0 or 1.
+
+GIT
+---
+Part of the linkgit:git[1] suite