How to let git pull from branch not from tag?

It seems the remote repository has a tag and a branch with the same name 0.9.0-rc6-patch1. Use the full name to fetch/pull,

# fetch/pull the tag
git fetch/pull origin refs/tags/0.9.0-rc6-patch1

# fetch/pull the branch
git fetch/pull origin refs/heads/0.9.0-rc6-patch1

You should use the full name like

git checkout refs/heads/<branchname>

or for tag

git checkout refs/tags/<refname>

For pull git pull origin refs/heads/<branchname>

To access the relevant documentation type in git help revisions

Refer the SPECIFYING REVISIONS section

Related