Permissions stripped during sed operation

[mjpitz]

Was trying to go through a few projects gh-pages. After doing a sed operation, the permissions of a file appear to be stripped:

$ ls -la _layouts/
total 32
drwxr-xr-x   4 jpitz  staff   128 May  2 06:46 .
drwxr-xr-x  13 jpitz  staff   416 May  2 06:45 ..
----------   1 jpitz  staff  5177 May  2 06:46 default.html
-rw-r--r--   1 jpitz  staff  4228 May  2 06:48 reference.html

Not sure what happened there but should be easy to reproduce:

$ ag -l <pattern> | xargs sed -i "s:<pattern>:<replace>:g"