.BI -C changesfile
Specifies the .changes file which is to be uploaded. By default
dgit push looks for single .changes file in the parent directory whose
-filename suggests it is for the right package and version.
+filename suggests it is for the right package and version - or,
+if there is a _multi.changes file, dgit uses that.
.TP
.BI --existing-package= package
dgit push needs to canonicalise the suite name. But currently