Fix for Get Device ID From SN keyword

Change-Id: Ia947c53eb750e4d0a5d589617cf8fdedfc3aa178
(cherry picked from commit 3d034e43dfeb7bc7891b1e67c4cbb9d1c456debc)
diff --git a/VERSION b/VERSION
index 2c9b4ef..a4dd9db 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.7.3
+2.7.4
diff --git a/libraries/voltctl.robot b/libraries/voltctl.robot
index 73015c7..4aa50d4 100755
--- a/libraries/voltctl.robot
+++ b/libraries/voltctl.robot
@@ -651,7 +651,6 @@
     ${rc}    ${id}=    Run and Return Rc and Output
     ...    voltctl -c ${VOLTCTL_CONFIG} device list --filter=SerialNumber=${serial_number} --format='{{.Id}}'
     Should Be Equal As Integers    ${rc}    0   "Error while fetching device list from VOLTHA"
-    Should Not Be Equal     ${id}   ${EMPTY}    Cannot find device by Serial Number ${serial_number}
     Log    ${id}
     [Return]    ${id}