exceptions.KeyboardInterrupt is thrown in gdb.base/random-signal.exp

[Yao Qi <qiyaoltc@gmail.com>]

Hi,
I am fixing a fail in gdb.base/random-signal.exp like this,

Continuing.^M
PASS: gdb.base/random-signal.exp: continue
^CPython Exception <type 'exceptions.KeyboardInterrupt'> <type 'exceptions.KeyboardInterrupt'>: ^M
FAIL: gdb.base/random-signal.exp: stop with control-c (timeout)

I only see this fail out of 15~20 runs each time.  Is it because GDB
received SIGINT before async_handle_remote_sigint is installed?  so
handle_sigint is still the SIGINT handler, set_quit_flag will call
python stuff, and KeyboardInterrupt is raised as a result.

In the test, we've already been aware of that the signal handler isn't
ready, so "Continuing" is consumed and ctrl-c is delayed in 500ms.

# For this to work we must be sure to consume the "Continuing."
# message first, or GDB's signal handler may not be in place.
after 500 {send_gdb "\003"}

After I read the tcl manul about "after", I feel the usage of "after"
above isn't 100% correct.  As the manual says, the "after" command
returns immediately, and the tcl command {send_gdb "\003"} will be
executed 500 ms later.  It is an asynchronous flavour, but what we want is
a synchronous operation, like this,

after 500
send_gdb "\003"

with this change, I don't see the timeout fail again.  Is it a fix or a
hack?

-- 
Yao (齐尧)

diff --git a/gdb/testsuite/gdb.base/random-signal.exp b/gdb/testsuite/gdb.base/random-signal.exp
index 566668a..59c8f5b 100644
--- a/gdb/testsuite/gdb.base/random-signal.exp
+++ b/gdb/testsuite/gdb.base/random-signal.exp
@@ -38,5 +38,6 @@ gdb_test_multiple "continue" "continue" {
 
 # For this to work we must be sure to consume the "Continuing."
 # message first, or GDB's signal handler may not be in place.
-after 500 {send_gdb "\003"}
+after 500
+send_gdb "\003"