py3: conditionalize BaseHTTPServer, SimpleHTTPServer and CGIHTTPServer import The BaseHTTPServer, SimpleHTTPServer and CGIHTTPServer has been merged into http.server in python 3. All of them has been merged as util.httpserver to use in both python 2 and 3. This patch adds a regex to check-code to warn against the use of BaseHTTPServer. Moreover this patch also includes updates to lower part of test-check-py3-compat.t which used to remain unchanged.