fix(scp): nounset mode suboption arg completion

Author: scop

completions/ssh

@@ -215,7 +215,7 @@ _ssh_suboption_check()
     # Get prev and cur words without splitting on =
     local cureq=$(_get_cword :=) preveq=$(_get_pword :=)
     if [[ $cureq == *=* && $preveq == -*o ]]; then
-        _ssh_suboption $cureq "$1"
+        _ssh_suboption $cureq "${1-}"
         return $?
     fi
     return 1

test/t/test_scp.py

@@ -77,3 +77,7 @@ def test_live(self, live_pwd, completion):
         ConnectTimeout and sleep_after_tab settings.
         """
         assert completion == f"{LIVE_HOST}:{live_pwd}/"
+
+    @pytest.mark.complete("scp -o Foo=")
+    def test_option_arg(self, completion):
+        assert not completion  # and no errors either