Fix for permission denied for Put File with correct permissions (#276)

Fixes #237

atest/put_file.robot

@@ -95,7 +95,30 @@ Putting Multiple Source Files To Single File Fails
     Run Keyword And Expect Error  ValueError: It is not possible to copy multiple source files to one destination file.
     ...                           Put File  ${LOCAL TEXTFILES}${/}?est*.txt  invalid.txt
 
+Put File Overwrite If User In The Same Group
+   Put File  ${LOCAL TEXTFILES}${/}${TEST FILE NAME}
+   SSH.File Should Exist  ${TEST FILE NAME}
+   Add testkey User To Group test And Set Permissions
+   Change User And Overwrite File
+   Switch Connection  1
+   SSH.File Should Exist  ${TEST FILE NAME}
+   [Teardown]  Remove testkey User From Group test And Cleanup
+
 *** Keywords ***
+Change User And Overwrite File
+    Open Connection  ${HOST}  prompt=${PROMPT}
+    Login With Public Key  ${KEY USERNAME}  ${KEY}
+    Put File  ${LOCAL TEXTFILES}${/}${TEST FILE NAME}  ${REMOTE HOME TEST}
+    [Teardown]  Close Connection
+
+Add testkey User To Group test And Set Permissions
+    Execute Command  usermod -a -G test testkey  sudo=True  sudo_password=test
+    Execute Command  chmod -R 660 ${TEST FILE NAME}
+
+Remove testkey User From Group test And Cleanup
+    Execute Command  gpasswd -d testkey test  sudo=True  sudo_password=test
+    Execute Command  rm -rf ${TEST FILE NAME}
+
 Remove Local Temp Dir And Remote File
     [Arguments]  ${path}
     Remove Directory  ${LOCAL TMPDIR}  yes

src/SSHLibrary/pythonclient.py

@@ -179,10 +179,12 @@ def _create_missing_remote_path(self, path, mode):
         return super(SFTPClient, self)._create_missing_remote_path(path, mode)
 
     def _create_remote_file(self, destination, mode):
+        file_exists = self.is_file(destination)
         destination = destination.encode(self._encoding)
         remote_file = self._client.file(destination, 'wb')
         remote_file.set_pipelined(True)
-        self._client.chmod(destination, mode)
+        if not file_exists:
+            self._client.chmod(destination, mode)
         return remote_file
 
     def _write_to_remote_file(self, remote_file, data, position):