Added /dev/pts to bind mount locations

During runtime several kernel filesystems are bind mounted into
the image root system such that programs expecting it can work.
/dev/pts was not needed so far but seems to be a good addition
to the list to make tools like sudo to work properly when called
e.g. from a config.sh script. This Fixes #2686

kiwi/system/root_bind.py

@@ -68,6 +68,7 @@ def __init__(self, root_init: RootInit):
         self.bind_locations = [
             '/proc',
             '/dev',
+            '/dev/pts',
             '/var/run/dbus',
             '/sys'
         ]

test/unit/system/root_bind_test.py

@@ -28,6 +28,15 @@ def setup(self):
         root.root_dir = 'root-dir'
         self.bind_root = RootBind(root)
 
+        # test expected real bind mount locations
+        assert self.bind_root.bind_locations == [
+            '/proc',
+            '/dev',
+            '/dev/pts',
+            '/var/run/dbus',
+            '/sys'
+        ]
+
         # stub config files and bind locations
         self.bind_root.config_files = ['/etc/sysconfig/proxy']
         self.bind_root.bind_locations = ['/proc']