test-shelve: do not use non-portable pipe-and

tests/test-shelve.t

@@ -1170,7 +1170,7 b' Try again but with a corrupted shelve st'
   [1]
   $ sed 's/ae8c668541e8/123456789012/' .hg/shelvedstate > ../corrupt-shelvedstate
   $ mv ../corrupt-shelvedstate .hg/histedit-state
-  $ hg unshelve --abort |& grep 'rebase aborted'
+  $ hg unshelve --abort 2>&1 | grep 'rebase aborted'
   rebase aborted
   $ hg up -C .
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved