[TestCompletion] Spawn LLDB with '--no-use-colors'.

Summary:
TestCompletion was broken for Ubuntu (and probably for Debian also).
The issue was that the lldb prompt in color (which is the default
behavior) was confusing pexpect.

Test Plan: "http://199.223.233.39:8011/lldb-try-clang-build-clang-test/"

Reviewers: zturner, clayborg

Reviewed By: clayborg

Subscribers: lldb-commits

Differential Revision: http://reviews.llvm.org/D6671

llvm-svn: 224642

lldb/test/functionalities/completion/TestCompletion.py

@@ -166,7 +166,8 @@ class CommandLineCompletionTestCase(TestBase):
         prompt = "(lldb) "
 
         # So that the child gets torn down after the test.
-        self.child = pexpect.spawn('%s %s' % (self.lldbHere, self.lldbOption))
+        self.child = pexpect.spawn(self.lldbHere,
+                                   [self.lldbOption] + ['--no-use-colors'])
         child = self.child
         # Turn on logging for input/output to/from the child.
         with open('child_send.txt', 'w') as f_send: