oeqa: tolerate interrupted select() while waiting for qemu

Sometimes, the OEQA utility code aborts with:

   ...
   File ".../meta/lib/oeqa/utils/qemurunner.py", line 131, in start
     return self.launch(launch_cmd, qemuparams=qemuparams, get_ip=get_ip, extra_bootparams=extra_bootparams)
   File ".../meta/lib/oeqa/utils/qemurunner.py", line 259, in launch
     sread, swrite, serror = select.select(socklist, [], [], 5)
  InterruptedError: [Errno 4] Interrupted system call

strace shows that this is because of a SIGWINCH:

   Connection from 127.0.0.1:52668
   select(21, [20], [], [], {5, 0})        = ? ERESTARTNOHAND (To be restarted if no handler)
   --- SIGWINCH {si_signo=SIGWINCH, si_code=SI_KERNEL} ---

This is related to some special conditions:
 * whether qemu opens a graphical console window (enabled in Poky by default)
 * where that window gets opened
 * whether the window manager changes the size of the shell window (mine
   is a tiling window manager and reorders and resizes windows automatically)

Ignoring the interrupted system calls avoids the problem. Code elsewhere (for example,
run() in ssh.py) already does the same thing.

(From OE-Core rev: 44fe106baf5fd5aebe26c5f28004e2b18d839b7c)

Signed-off-by: Patrick Ohly <patrick.ohly@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/utils/qemurunner.py

@@ -256,7 +256,10 @@ class QemuRunner:
             bootlog = ''
             data = b''
             while time.time() < endtime and not stopread:
-                sread, swrite, serror = select.select(socklist, [], [], 5)
+                try:
+                    sread, swrite, serror = select.select(socklist, [], [], 5)
+                except InterruptedError:
+                    continue
                 for sock in sread:
                     if sock is self.server_socket:
                         qemusock, addr = self.server_socket.accept()
@@ -437,7 +440,10 @@ class QemuRunner:
             if now >= end:
                 data += "<<< run_serial(): command timed out after %d seconds without output >>>\r\n\r\n" % timeout
                 break
-            sread, _, _ = select.select([self.server_socket],[],[], end - now)
+            try:
+                sread, _, _ = select.select([self.server_socket],[],[], end - now)
+            except InterruptedError:
+                continue
             if sread:
                 answer = self.server_socket.recv(1024)
                 if answer:

meta/lib/oeqa/utils/qemutinyrunner.py

@@ -114,7 +114,10 @@ class QemuTinyRunner(QemuRunner):
         stopread = False
         endtime = time.time()+timeout
         while time.time()<endtime and not stopread:
-                sread, _, _ = select.select([self.server_socket],[],[],1)
+                try:
+                        sread, _, _ = select.select([self.server_socket],[],[],1)
+                except InterruptedError:
+                        continue
                 for sock in sread:
                         answer = sock.recv(1024)
                         if answer: