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.

hgext/strip.py

@@ -78,9 +78,6 b' def strip(ui, repo, revs, update=True, b'
                                'option)'), _('REV')),
           ('f', 'force', None, _('force removal of changesets, discard '
                                  'uncommitted changes (no backup)')),
-          ('b', 'backup', None, _('bundle only changesets with local revision'
-                                  ' number greater than REV which are not'
-                                  ' descendants of REV (DEPRECATED)')),
           ('', 'no-backup', None, _('no backups')),
           ('', 'nobackup', None, _('no backups (DEPRECATED)')),
           ('n', '', None, _('ignored  (DEPRECATED)')),

tests/test-strip.t

@@ -524,4 +524,28 b' test hg strip -B bookmark'
   $ hg bookmarks
    * B                         6:ff43616e5d0f
 
-  $ cd ..
+Make sure no one adds back a -b option:
+
+  $ hg strip -b tip
+  hg strip: option -b not recognized
+  hg strip [-k] [-f] [-n] [-B bookmark] [-r] REV...
+  
+  strip changesets and all their descendants from the repository
+  
+  use "hg help -e strip" to show help for the strip extension
+  
+  options:
+  
+   -r --rev REV [+]    strip specified revision (optional, can specify revisions
+                       without this option)
+   -f --force          force removal of changesets, discard uncommitted changes
+                       (no backup)
+      --no-backup      no backups
+   -k --keep           do not modify working copy during strip
+   -B --bookmark VALUE remove revs only reachable from given bookmark
+      --mq             operate on patch repository
+  
+  [+] marked option can be specified multiple times
+  
+  use "hg help strip" to show the full help text
+  [255]