Added \r\n to the expect() string as recomended at:
http://pexpect.readthedocs.io/en/stable/overview.html#find-the-end-of-line-cr-lf-conventions
this should work on both windows and linux systems
pexpect says it will always do a minimal (non greedy) matching and docs explicitly say that a .+ expression will always return only one character. These lines in autotest are looking for \S+, which, believing the documentation, would only return one character of the log file path.
Now we know that's not true, neither for Linux or for Windows (given the logs from @karthikdesai), so I can only assume that it does a greedy match but only for the characters it has received at the time expect is called.
Apparently, in the machines we are using autotest, it isn't a problem since MAVProxy is likely fast to give its output to pexpect before the expect method is called. On @karthikdesai's machine that wasn't happening since his machine was more or less loaded.
Concluding, this looks like a correct fix in the sense that it extends the regex pattern to wait for the end of line (and probably other places could benefit from it too).
5c07a44a6d