mypy, mysql, xmms: don't complete unknown split long option args

Closes #303

completions/mypy

@@ -43,6 +43,8 @@ _mypy()
             ;;
     esac
 
+    $split && return
+
     if [[ $cur == -* ]]; then
         COMPREPLY=( $(compgen -W '$(_parse_help "$1")' -- "$cur") )
         return

completions/mysql

@@ -69,6 +69,8 @@ _mysql()
             ;;
     esac
 
+    $split && return
+
     case $cur in
         --*)
             local help=$(_parse_help "$1")

completions/xmms

@@ -15,6 +15,8 @@ _xmms()
             ;;
     esac
 
+    $split && return
+
     if [[ "$cur" == -* ]]; then
         COMPREPLY=( $(compgen -W '$(_parse_help "$1")' -- "$cur") )
     else

test/t/test_mypy.py

@@ -9,3 +9,7 @@ def test_1(self, completion):
     @pytest.mark.complete("mypy --")
     def test_2(self, completion):
         assert completion
+
+    @pytest.mark.complete("mypy --non-existent-option=--")
+    def test_3(self, completion):
+        assert not completion

test/t/test_mysql.py

@@ -9,3 +9,7 @@ def test_1(self, completion):
     @pytest.mark.complete("mysql --default-character-set=")
     def test_2(self, completion):
         assert completion
+
+    @pytest.mark.complete("mysql --non-existent-option=--")
+    def test_3(self, completion):
+        assert not completion

test/t/test_xmms.py

@@ -5,3 +5,7 @@ class TestXmms:
     @pytest.mark.complete("xmms --")
     def test_1(self, completion):
         assert completion
+
+    @pytest.mark.complete("xmms --non-existent-option=--")
+    def test_2(self, completion):
+        assert not completion