I'm following this guide to create a debdiff for a package I'm patching. Everything goes fine until step number 8 and I attempt to create the debdiff after committing the changes. The package in question is Zim, pulled form Launchpad using

bzr branch lp:zim

and according to this guide I should execute the following command to create the debdiff:

debdiff zim_0.49.dsc zim_0.49ubuntu1.dsc > zim_0.49ubuntu1.debdiff

however, when I actually try to execute this command, I get the following error:

debdiff: fatal error at line 314:
Can't read file: zim_0.49.dsc

Upon inspection of the directory in which the files created from debuild -S (step 6) are deposited, I find

zim_0.49ubuntu1_source.changes
zim_0.49ubuntu1.dsc           
zim_0.49ubuntu1.tar.gz
zim_0.49ubuntu1_source.build

but no sign of zim_0.49.dsc. I could probably create one by debuilding the package as soon as I check out the code, before starting work, but that would add an extraneous entry in the changelog.

Is there a step missing from the guide that creates zim_0.49.dsc or is the file itself missing from the source?