test-patchbomb: sed -e may not work with extended regexps

Non-GNU versions of the sed(1) utility (i.e. on Solaris or BSD)
may not support extended regexps (i.e. including \| branches),
or may need a special option to enable it (like -E instead of -e).

Expand the sed RE in tests/test-patchbomb to fix running this
test on FreeBSD and Solaris.

tests/test-patchbomb

@@ -14,6 +14,7 b' echo b > b'
 hg commit -Amb -d '2 0'
 
 hg email --date '1970-1-1 0:2' -n -f quux -t foo -c bar -s test 0:tip | \
-  sed -e 's/\(Message-Id:.*@\|In-Reply-To:.*@\).*/\1/'
+  sed -e 's/\(Message-Id:.*@\).*/\1/' | \
+  sed -e 's/\(In-Reply-To:.*@\).*/\1/'
 
 hg email -m test.mbox -f quux -t foo -c bar -s test 0:tip