Store full sha in branch model

The model will be used for logic, so the full hash is needed there; a shortened
hash of 8 characters might be too short to be unique in very large repos. If
some view wants to display a shortened hash, it should truncate it at
presentation time.

pkg/commands/git_commands/branch_loader.go

@@ -171,7 +171,7 @@ var branchFields = []string{
 	"upstream:short",
 	"upstream:track",
 	"subject",
-	fmt.Sprintf("objectname:short=%d", utils.COMMIT_HASH_SHORT_SIZE),
+	"objectname",
 }
 
 // Obtain branch information from parsed line output of getRawBranches()