test: avoid interrupting magic mark output

The same race condition as 85275cf exists for multiple completions
(case 0).  If the magic mark is not included in `expect()`, it may or
may not have been written by bash at the point `bash.sendintr()` is
called.   If the interrupt is delivered before magic mark has finished
printing, it can corrupt the prompt and cause `bash.expect_exact(PS1)`
to timeout.

Include `MAGIC_MARK` in the case 0 regex to avoid this issue.

Signed-off-by: Kevin Locke <kevin@kevinlocke.name>

test/t/conftest.py

@@ -357,9 +357,12 @@ def assert_complete(
     bash.expect_exact(cmd)
     bash.send(MAGIC_MARK)
     got = bash.expect([
-        r"\r\n" + re.escape(PS1 + cmd),  # 0: multiple lines, result in .before
-        r"^" + MAGIC_MARK,               # 1: no completion
-        r"^([^\r]+)%s$" % MAGIC_MARK,    # 2: on same line, result in .match
+        # 0: multiple lines, result in .before
+        r"\r\n" + re.escape(PS1 + cmd) + ".*" + MAGIC_MARK,
+        # 1: no completion
+        r"^" + MAGIC_MARK,
+        # 2: on same line, result in .match
+        r"^([^\r]+)%s$" % MAGIC_MARK,
         pexpect.EOF,
         pexpect.TIMEOUT,
     ])