Git 如何把master的内容更新到分支

Background：

　　当有人对master进行更新之后，你想让已经创建的分支内容更新到master的最新状态，

bpan@5CG7022BM2 MINGW64 /d/GitRep/JIRA_Extensions (master)
$ git checkout 20180315  //切换到分支下
Switched to branch ''
Your branch is behind 'origin/master' by  commits, and can be fast-forwarded.
  (use "git pull" to update your local branch)

bpan@5CG7022BM2 MINGW64 /d/GitRep/JIRA_Extensions ()
$ git merge master  //合并master到分支，
Updating cee69ca..8b0ec9a
Fast-forward
 .gitignore                                         |    +
 .../functions/ExtractGroupMembersToExcelFile.java  |  +++++++++++++++++++++
  files changed,  insertions(+)
 create mode  src/main/java/com/nokia/jira/functions/ExtractGroupMembersToExcelFile.java

bpan@5CG7022BM2 MINGW64 /d/GitRep/JIRA_Extensions ()
$ git status
On branch
Your branch is up-to-date with 'origin/master'.
nothing to commit, working tree clean

bpan@5CG7022BM2 MINGW64 /d/GitRep/JIRA_Extensions ()
$ git push origin 20180315  //push到远程分支
fatal: HttpRequestException encountered.
   An error occurred while sending the request.
Username for 'https://github.com':
Total  (delta ), reused  (delta )
To https://github.com/962720900/JiraExtensionFunctions.git
   e713274..8b0ec9a   ->