helpers.package.get: fix replace_subpkgnames, !ret
(It seems we don't have a code path hitting this right now, but I ran into this while debugging pmaports!5619)
Don't attempt to replace subpackages, if we didn't find a package so far.
Fix for:
File "/home/user/code/pmbootstrap/pmb/helpers/package.py", line 117, in get
for depend in ret["depends"]:
~~~^^^^^^^^^^^
KeyError: 'depends'