# HG changeset patch
# User Boris Feld <boris.feld@octobus.net>
# Date 1544804741 -3600
# Node ID 2e305e54eae317f4ce98a1b0b68e78b8cacc8aa9
# Parent  c6939b353ebd2b5b6fe383bd009a5315d52717c6
sparse-revlog: protect C code against delta chain including nullrev

For unclear reasons, some repositories include nullrev (-1). Re-computing
delta for such repo remove nullrev from all chain, so some older versions have
been creating them.

This currently raise an IndexError with the new C code doing chain slicing as
it expect all item to be positive.

Both python and C code for reading delta chain preserve nullrev, and the Python
code for chain slicing handle the case fine. So we take the safe route and make
the new C code works fine in that case.

diff -r c6939b353ebd -r 2e305e54eae3 mercurial/cext/revlog.c
--- a/mercurial/cext/revlog.c	Fri Dec 14 17:24:44 2018 +0100
+++ b/mercurial/cext/revlog.c	Fri Dec 14 17:25:41 2018 +0100
@@ -1229,7 +1229,7 @@
 		if (revnum == -1 && PyErr_Occurred()) {
 			goto bail;
 		}
-		if (revnum < 0 || revnum >= idxlen) {
+		if (revnum < nullrev || revnum >= idxlen) {
 			PyErr_Format(PyExc_IndexError,
 			             "index out of range: %zd", revnum);
 			goto bail;