strip: drop -b/--backup option (BC)
This option had very limited utility and counterintuitive behavior and
collided unfortunately with the much later -B option.
Normally we would no-op such a feature so as to avoid annoying existing
scripts. However, we have to weigh that against the silent misbehavior
that results when users mistakenly intended to use -B: because -b
takes no arg, the bookmark gets interpreted as a normal revision, and
gets stripped without removing the associated bookmark, while also not
backing up the revision in question. A no-op behavior or warning would only
remove the latter half of the misadventure.
The only users I can find of this feature were using it in error and
have since stopped. The few (if any) remaining users of this feature
would be better served by --no-backup.
$ hg init
$ cat > a <<EOF
> a
> b
> c
> EOF
$ hg ci -Am adda
adding a
$ cat > a <<EOF
> d
> e
> f
> EOF
$ hg ci -m moda
$ hg diff --reverse -r0 -r1
diff -r 2855cdcfcbb7 -r 8e1805a3cf6e a
--- a/a Thu Jan 01 00:00:00 1970 +0000
+++ b/a Thu Jan 01 00:00:00 1970 +0000
@@ -1,3 +1,3 @@
-d
-e
-f
+a
+b
+c
$ cat >> a <<EOF
> g
> h
> EOF
$ hg diff --reverse --nodates
diff -r 2855cdcfcbb7 a
--- a/a
+++ b/a
@@ -1,5 +1,3 @@
d
e
f
-g
-h