qemurunner.py: Performance improvements in run_serial

This allow to search for the prompt after a command is
run so it can avoid waiting for the timeout.

Also corrected identation issues

[YOCTO #8118]

(From OE-Core rev: 600f35c0873a61f8cd02c0e5cc1495ce7785ea89)

Signed-off-by: Mariano Lopez <mariano.lopez@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/utils/qemurunner.py

@@ -284,14 +284,18 @@ class QemuRunner:
         stopread = False
         endtime = time.time()+5
         while time.time()<endtime and not stopread:
-                sread, _, _ = select.select([self.server_socket],[],[],5)
-                for sock in sread:
-                        answer = sock.recv(1024)
-                        if answer:
-                                data += answer
-                        else:
-                                sock.close()
-                                stopread = True
+            sread, _, _ = select.select([self.server_socket],[],[],5)
+            for sock in sread:
+                answer = sock.recv(1024)
+                if answer:
+                    data += answer
+                    # Search the prompt to stop
+                    if re.search("[a-zA-Z0-9]+@[a-zA-Z0-9\-]+:~#", data):
+                        stopread = True
+                        break
+                else:
+                    sock.close()
+                    stopread = True
         if data:
             if raw:
                 status = 1