block: Improve message for device name clashing with node name

Suggested-by: NBenoit Canet <benoit.canet@nodalink.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NBenoît Canet <benoit.canet@nodalink.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block.c

@@ -347,7 +347,8 @@ BlockDriverState *bdrv_new(const char *device_name, Error **errp)
         return NULL;
     }
     if (bdrv_find_node(device_name)) {
-        error_setg(errp, "Device with node-name '%s' already exists",
+        error_setg(errp,
+                   "Device name '%s' conflicts with an existing node name",
                    device_name);
         return NULL;
     }

tests/qemu-iotests/087.out

@@ -20,7 +20,7 @@ QMP_VERSION
 {"return": {}}
 {"return": {}}
 {"error": {"class": "GenericError", "desc": "Device with id 'disk' already exists"}}
-{"error": {"class": "GenericError", "desc": "Device with node-name 'test-node' already exists"}}
+{"error": {"class": "GenericError", "desc": "Device name 'test-node' conflicts with an existing node name"}}
 main-loop: WARNING: I/O thread spun for 1000 iterations
 {"error": {"class": "GenericError", "desc": "could not open disk image disk2: node-name=disk is conflicting with a device id"}}
 {"error": {"class": "GenericError", "desc": "could not open disk image disk2: Duplicate node name"}}