tests/test-diffdir.out

Hook fixups

Pass the first new changeset node to the changegroup hook
Call commit for each changeset in a pull changegroup
Improve hook docs

diff -r 3903775176ed b
--- /dev/null
+++ b/b
@@ -0,0 +1,1 @@
+123
diff -r 3903775176ed b
--- /dev/null
+++ b/b
@@ -0,0 +1,1 @@
+123