status: add the --change option to display files changed in a revision
This option is similar to the one already used for the diff command.
Unfortunately, the c and C short option are already used for status, so there
is no corresponding short option. However, there is no short option for --rev
either, so that's consistent.
% init
adding a
% fold in the middle of the queue
popping p3
popping p2
now at: p1
--- a/a
+++ b/a
@@ -1,1 +1,2 @@
a
+a
p1
p3
--- a/a
+++ b/a
@@ -1,1 +1,3 @@
a
+a
+b
% fold with local changes
abort: local changes found, refresh first
--- a/a
+++ b/a
@@ -1,1 +1,3 @@
a
+a
+b