diff -r 8ddfdcce4bd6 -r 3fb0493812c0 mercurial/commands.py
--- a/mercurial/commands.py	Wed Jul 10 23:11:55 2019 +0530
+++ b/mercurial/commands.py	Wed Jun 26 22:15:07 2019 +0530
@@ -6182,6 +6182,12 @@
     with repo.wlock():
         return shelvemod.dounshelve(ui, repo, *shelved, **opts)
 
+statemod.addunfinished(
+    'unshelve', fname='shelvedstate', continueflag=True,
+    abortfunc=shelvemod.hgabortunshelve,
+    cmdmsg=_('unshelve already in progress'),
+)
+
 @command('update|up|checkout|co',
     [('C', 'clean', None, _('discard uncommitted changes (no backup)')),
     ('c', 'check', None, _('require clean working directory')),