unshelve: abort on using --keep and --interactive together

I am working on making interactive mode support `--keep` flag. Until
we support the usage of `--interactive` and `--keep` together, let
us abort on it.

Differential Revision: https://phab.mercurial-scm.org/D6699

mercurial/shelve.py

@@ -942,6 +942,8 b' def dounshelve(ui, repo, *shelved, **opt'
     if opts.get("name"):
         shelved.append(opts["name"])
 
+    if interactive and opts.get('keep'):
+        raise error.Abort(_('--keep on --interactive is not yet supported'))
     if abortf or continuef:
         if abortf and continuef:
             raise error.Abort(_('cannot use both abort and continue'))

tests/test-shelve.t

@@ -1475,3 +1475,7 b' Abort unshelve while merging (issue5123)'
   record this change to 'bar2'?
   (enter ? for help) [Ynesfdaq?] y
   
+-- test for --interactive --keep
+  $ hg unshelve -i --keep
+  abort: --keep on --interactive is not yet supported
+  [255]