Thanks to Raphaël Hertzog for spotting the issue
when investigating build errors in dpkg's Jenkins job.
JFTR:
| jenkins@grml-jenkins:~/jobs/dpkg-source/workspace/source$ git pull
| Updating fb18783..91495b8
| error: Your local changes to 'debian/changelog' would be overwritten by merge. Aborting.
| Please, commit your changes or stash them before you can merge.
| jenkins@grml-jenkins:~/jobs/dpkg-source/workspace/source$
When a foobar_0.42.orig.tar.gz is found then debian/control isn't
present necessarily, so make sure we don't try to access debian/control
if it's not available.
For the timestamp we're now using seconds since 1970 (date +%s).
This will always increase over time whereas svn revisions might
not be consistent over all the time and building on slaves might
cause lower build numbers.
So lets use ...~${TIMESTAMP}.svn${SVN_REVISION}.${BUILD_NUMBER}"
as the version schema to get increasing version numbers no matter
what.