They way we were attempting to get return codes before always gave
us a return code of the previous echo, therefore always `0`.
This commit adds the newline into the last echo.
As of ADB 1.0.35/Android N, it will return the exit code of the command that it runs
This code handles this scenario as before WA treated a return code from ADB as an
error with ADB.
- android/workload: emoved an extra bank line between methods
- trace_cmd: define member attribute inside __init__
- adb_shell: ignore pylint warning about too many branches in this case
In order to execute as root, the command string gets echo'd into so;
previusly, double quotes were used in echo, which caused any veriables
in the command string to be expanded _before_ it was echoed.
- adb protcol uses "\r\n" for line breaks. This is not handled by
Python's line break translation, as not a file. So spliting on '\n'
when extracting the exit code resulted in stray '\r' in the output.
- adb_shell expects exit code to be echoed on the same line. This may
not have been the case if latest output from executed command was not
a complete line. An extra echo will now ensure that the exit code will
be on its own line even in that case.
