Linearized document causes error: Cannot remove last revision

```
1. Read in a linearized document
2. Write out the linearized document to a new file
3. Error

I'm using the latest gem version 1.2.4.

I've tried adding delinearize => false but the resulting PDF is invalid.

I can't attach the file here as it's a commercial document but I'd be happy to
send it via email.

```

Original issue reported on code.google.com by `haruki.z...@gmail.com` on 26 Nov 2012 at 12:39