pushTo: leads to error on some branches

[chisandrei]

Example code below. self can be any iceberg repository where the current branch has a remote.

self branch fullname. "'refs/heads/release'"
(self branchNamed: self branch name) name. "'release'"

self branch pushTo: self branch upstream remote. "Works as expected"
(self branchNamed: self branch name) pushTo: self branch upstream remote. "IceGenericError: Not a valid reference ''release''"

Doing self branch pushTo: self branch upstream remote works as expected. But using branchNamed: to obtain the branch and then calling pushTo: fails with an exception. The different between the two braches is their full name. In one case it refs/heads/release in the other release