Add a simple remove test

tests/test-remove

@@ -0,0 +1,13 b''
+#!/bin/sh
+
+hg init a
+cd a
+echo a > foo
+hg add foo
+hg commit -m 1 -d "0 0"
+rm foo
+hg remove foo
+hg commit -m 2 -d "0 0"
+
+cd ..
+hg clone a b