[PATCH 3/3] t/lib-rebase: improve documentation of set_fake_editor()

[Oswald Buddenhagen <oswald.buddenhagen@gmx.de>]

- Make it reflect better what actually happens. This makes it easier to
  fully exploit the possibilities and to modify the code.
- Improve the structure, putting more general info further up.
- Document `fakesha` and `break`.

Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
---
Cc: Phillip Wood <phillip.wood123@gmail.com>
---
 t/lib-rebase.sh | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/t/lib-rebase.sh b/t/lib-rebase.sh
index 9ed87ca7ab..184b25b427 100644
--- a/t/lib-rebase.sh
+++ b/t/lib-rebase.sh
@@ -8,18 +8,21 @@
 # - check that non-commit messages have a certain line count with $EXPECT_COUNT
 # - check the commit count in the commit message header with $EXPECT_HEADER_COUNT
 # - rewrite a rebase -i script as directed by $FAKE_LINES.
-#   $FAKE_LINES consists of a sequence of words separated by spaces.
-#   The following word combinations are possible:
+#   $FAKE_LINES consists of a sequence of words separated by spaces;
+#   spaces inside the words are encoded as underscores.
+#   The following words are possible:
 #
-#   "<lineno>" -- add a "pick" line with the SHA1 taken from the
-#       specified line.
+#   "<cmd>" -- override the command for the next line specification. Can be
+#       "pick", "squash", "fixup"|"fixup_-C"|"fixup_-c", "edit", "reword",
+#       "drop", "merge[_-{c|C}_<SHA1>]", or "bad" for an invalid command.
 #
-#   "<cmd> <lineno>" -- add a line with the specified command
-#       ("pick", "squash", "fixup"|"fixup_-C"|"fixup_-c", "edit", "reword" or "drop")
-#       and the SHA1 taken from the specified line.
+#   "<lineno>" -- add a command, using the specified line as a template.
+#       If the command has not been overridden, the line will be copied
+#       verbatim, usually resulting in a "pick" line.
 #
-#   "_" -- add a space, like "fixup_-C" implies "fixup -C" and
-#       "exec_cmd_with_args" add an "exec cmd with args" line.
+#   "fakesha" -- add a command ("pick" by default), using a fake SHA1.
+#
+#   "exec_[...]", "break" -- add the specified command.
 #
 #   "#" -- Add a comment line.
 #
-- 
2.40.0.152.g15d061e6df