title: git diff commits do not shows all the changed files' difference
body: <p>When I from <code>master</code> branch merge a branch(<code>wxc</code>):</p>
  
  <pre><code>$ git merge wxc
  Merge made by the 'recursive' strategy.
   Q2/__init__.py                                                                |   3 +
   Q2/common/GLOBAL_CONST.py                                                     |   8 +--
   Q2/urls.py                                                                    |   7 ---
   .../admin_productconfig_physicalserver/api/paginations.py"                   |   1 +
   .../admin_productconfig_physicalserver/api/serializers.py"                   |  22 ++++++-
   .../admin_productconfig_physicalserver/api/switch_cmd_util.py"               |  31 +---------
   .../admin_productconfig_physicalserver/api/urls.py"                          |   6 ++
   .../admin_productconfig_physicalserver/api/views.py"                         | 133 +++++++++++++++++++++++++++++++++++++++-
   .../admin_productconfig_physicalserver/migrations/0091_mg.py"                |  34 ++++++++++
   .../admin_productconfig_physicalserver/migrations/0092_mgnumber.py"          |  25 ++++++++
   .../migrations/0093_auto_20190902_1249.py"                                         |  19 ++++++
   .../migrations/0094_merge_20190906_0822.py"                                        |  16 +++++
   .../admin_productconfig_physicalserver/models.py"                            |  61 ++++++++++++++++--
   .../admin_usermanage/api/serializers.py"                                     |   2 +-
   .../admin_usermanage/api/views.py"                                           |   4 +-
   15 files changed, 318 insertions(+), 54 deletions(-)
   create mode 100644 "\346\227\227\344\272\221\347\256\241\347\220\206\345\221\230\345\220\216\345\217\260/\344\272\247\345\223\201\351\205\215\347\275\256/qiyun_admin_productconfig_physicalserver/migrations/0091_mg.py"
   create mode 100644 "\346\227\227\344\272\221\347\256\241\347\220\206\345\221\230\345\220\216\345\217\260/\344\272\247\345\223\201\351\205\215\347\275\256/qiyun_admin_productconfig_physicalserver/migrations/0092_mgnumber.py"
   create mode 100644 "\346\227\227\344\272\221\347\256\241\347\220\206\345\221\230\345\220\216\345\217\260/\344\272\247\345\223\201\351\205\215\347\275\256/qiyun_admin_productconfig_physicalserver/migrations/0093_auto_20190902_1249.py"
   create mode 100644 "\346\227\227\344\272\221\347\256\241\347\220\206\345\221\230\345\220\216\345\217\260/\344\272\247\345\223\201\351\205\215\347\275\256/qiyun_admin_productconfig_physicalserver/migrations/0094_merge_20190906_0822.py"
  </code></pre>
  
  <p>You see there are so many files changes, such as the <code>Q2/__init__.py</code>, <code>Q2/common/GLOBAL_CONST.py</code>, <code>Q2/urls.py</code> and so on:</p>
  
  <p>then I check my <code>master</code> brach's latest two logs:</p>
  
  <pre><code>$ git log -n2
  commit b63c3856677916f8008b338c139bd3b00c90593d (HEAD -&gt; master)
  Merge: 6b59b80 3e85a8d
  Author: dale &lt;dale@gmail.com&gt;
  Date:   Wed Sep 18 11:28:25 2019 +0800
  
      Merge branch 'wxc 20190917-wxc'
  
  commit 3e85a8dfd0270f6fb0f3786b8761038df322890f (remote_repo/wxc, wxc)
  Author: dale &lt;dale@gmail.com&gt;
  Date:   Tue Sep 17 16:04:54 2019 +0800
  
      '2019-09-17-wxc-01'
  </code></pre>
  
  <p>I want to compare the latest two commits' difference:</p>
  
  <pre><code>dale-MBP:Q2 ldl$ git diff 3e85a8df b63c3856
  diff --git "a/\346\227\227\344\272\221\347\256\241\347\220\206\345\221\230\345\220\216\345\217\260/\344\272\247\345\223\201\351\205\215\347\275\256/admin_productconfig_physicalserver/api/whmcs/views.py" "b/\346\227\227\344\272\221\347\256\241\347\220\206\345\221\230\345\220\216\345\217\260/\344\272\247\345\223\201\351\205\215\347\275\256/admin_productconfig_physicalserver/api/whmcs/views.py"
  index ccc1ba3..9fac902 100644
  --- "a/\346\227\227\344\272\221\347\256\241\347\220\206\345\221\230\345\220\216\345\217\260/\344\272\247\345\223\201\351\205\215\347\275\256/admin_productconfig_physicalserver/api/whmcs/views.py"
  +++ "b/\346\227\227\344\272\221\347\256\241\347\220\206\345\221\230\345\220\216\345\217\260/\344\272\247\345\223\201\351\205\215\347\275\256/admin_productconfig_physicalserver/api/whmcs/views.py"
  @@ -74,8 +74,11 @@ class WHMCSPhysicalServerIPMIManagementAPIView(APIView):
  
               if whmcs_site not in [
                   "www.44.hk",
  +                "44.hk",
                   "www.44.com",
  -                "www.44.net"
  +                "44.com",
  +                "www.44.net",
  +                "44.net"
               ]:
                   return Response(status=HTTP_400_BAD_REQUEST, data="error")
  
  @@ -100,6 +103,8 @@ class WHMCSPhysicalServerIPMIManagementAPIView(APIView):
               physical_server_name = request.data.get('physical_server_name')
               action = request.data.get('action')
  
  +            physical_server_name = str(physical_server_name).split("/")[0]
  +
               if not physical_server_name or not action:
                   return Response(data="invalid request data", status=HTTP_400_BAD_REQUEST)
  </code></pre>
  
  <p>you see there only compare one file(<code>admin_productconfig_physicalserver/api/whmcs/views.py</code>), why there do not compare the other files? and the other question is the  <code>admin_productconfig_physicalserver/api/whmcs/views.py</code> did not exist in the <code>merge</code> file changed list:</p>
  
  <pre><code> Q2/__init__.py                                                                |   3 +
   Q2/common/GLOBAL_CONST.py                                                     |   8 +--
   Q2/urls.py                                                                    |   7 ---
   .../admin_productconfig_physicalserver/api/paginations.py"                   |   1 +
   .../admin_productconfig_physicalserver/api/serializers.py"                   |  22 ++++++-
   .../admin_productconfig_physicalserver/api/switch_cmd_util.py"               |  31 +---------
   .../admin_productconfig_physicalserver/api/urls.py"                          |   6 ++
   .../admin_productconfig_physicalserver/api/views.py"                         | 133 +++++++++++++++++++++++++++++++++++++++-
   .../admin_productconfig_physicalserver/migrations/0091_mg.py"                |  34 ++++++++++
   .../admin_productconfig_physicalserver/migrations/0092_mgnumber.py"          |  25 ++++++++
   .../migrations/0093_auto_20190902_1249.py"                                         |  19 ++++++
   .../migrations/0094_merge_20190906_0822.py"                                        |  16 +++++
   .../admin_productconfig_physicalserver/models.py"                            |  61 ++++++++++++++++--
   .../admin_usermanage/api/serializers.py"                                     |   2 +-
   .../admin_usermanage/api/views.py"                                           |   4 +-
   15 files changed, 318 insertions(+), 54 deletions(-)
   create mode 100644 "\346\227\227\344\272\221\347\256\241\347\220\206\345\221\230\345\220\216\345\217\260/\344\272\247\345\223\201\351\205\215\347\275\256/qiyun_admin_productconfig_physicalserver/migrations/0091_mg.py"
   create mode 100644 "\346\227\227\344\272\221\347\256\241\347\220\206\345\221\230\345\220\216\345\217\260/\344\272\247\345\223\201\351\205\215\347\275\256/qiyun_admin_productconfig_physicalserver/migrations/0092_mgnumber.py"
   create mode 100644 "\346\227\227\344\272\221\347\256\241\347\220\206\345\221\230\345\220\216\345\217\260/\344\272\247\345\223\201\351\205\215\347\275\256/qiyun_admin_productconfig_physicalserver/migrations/0093_auto_20190902_1249.py"
   create mode 100644 "\346\227\227\344\272\221\347\256\241\347\220\206\345\221\230\345\220\216\345\217\260/\344\272\247\345\223\201\351\205\215\347\275\256/qiyun_admin_productconfig_physicalserver/migrations/0094_merge_20190906_0822.py"
  </code></pre>