oeqa/core/runner: OEStreamLogger don't buffer test execution writes

Since OEQA framework uses Python logging functionality to report test
results there is a class that wraps PyUnit writes into logging commands
(OEStreamLogger), so don't buffer the actual test execution to have
insight of what is currently executing.

This fix will change a little the test output format adding an '\n'
previous the test result, for example:

From:

test_nonmatching_checksum (lic_checksum.LicenseTests) ... ok

To:

test_nonmatching_checksum (lic_checksum.LicenseTests)
 ... ok

This is because the new line added by the PyUnit StreamLogger because
currently we don't have a manner to identify when a test execution
starts at report level (write msg).

[YOCTO #11827]

(From OE-Core rev: 4c2276469f58a88f864eb374c00dbbaace702de4)

Signed-off-by: Aníbal Limón <anibal.limon@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/core/runner.py

@@ -25,10 +25,14 @@ class OEStreamLogger(object):
 
     def write(self, msg):
         if len(msg) > 1 and msg[0] != '\n':
-            self.buffer += msg
-        else:
-            self.logger.log(logging.INFO, self.buffer.rstrip("\n"))
-            self.buffer = ""
+            if '...' in msg:
+                self.buffer += msg
+            elif self.buffer:
+                self.buffer += msg
+                self.logger.log(logging.INFO, self.buffer)
+                self.buffer = ""
+            else:
+                self.logger.log(logging.INFO, msg)
 
     def flush(self):
         for handler in self.logger.handlers: