git-debrebase(5): Document new understanding of debrebase-last

Bug #907208 shows that the previous statement wasn't true.

debrebase-last is still marginally useful: we use it for deciding what
hints to print in some error messages; detecting and rejecting
attempts to convert already-converted branches; and in
`git-debrebase status'.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

diff --git a/git-debrebase.5.pod b/git-debrebase.5.pod
index e3ed30930b43c81d90556de5b747e092a04122bd..439fd63b89b30155960ae5821c6f19ca3571b677 100644 (file)
--- a/git-debrebase.5.pod
+++ b/git-debrebase.5.pod
@@ -378,8 +378,11 @@ from the interchange branch and no pseudomerge is needed.
 When ffq-prev is not present,
 C<refs/debrebase-last/B> records some ancestor of refs/B,
 (usually, the result of last stitch).
-This can be used to quickly determine whether refs/B
-is being maintained in git-debrebase form.
+This is used for status printing and some error error checks -
+especially for printing guesses what a problem is.
+To determine whether a branch is 
+is being maintained in git-debrebase form
+it is necessary to walk its history.
 
 =head1 OTHER MERGES