lint: Make sure we read the command line inputs using utf-8 decoding in python

test/lint/check-doc.py

@@ -26,8 +26,8 @@ SET_DOC_OPTIONAL = set(['-rpcssl', '-benchmark', '-h', '-help', '-socks', '-tor'
 
 
 def main():
-    used = check_output(CMD_GREP_ARGS, shell=True, universal_newlines=True)
-    docd = check_output(CMD_GREP_DOCS, shell=True, universal_newlines=True)
+    used = check_output(CMD_GREP_ARGS, shell=True, universal_newlines=True, encoding='utf8')
+    docd = check_output(CMD_GREP_DOCS, shell=True, universal_newlines=True, encoding='utf8')
 
     args_used = set(re.findall(re.compile(REGEX_ARG), used))
     args_docd = set(re.findall(re.compile(REGEX_DOC), docd)).union(SET_DOC_OPTIONAL)

test/lint/lint-python-utf8-encoding.sh

@@ -17,4 +17,12 @@ if [[ ${OUTPUT} != "" ]]; then
     echo "${OUTPUT}"
     EXIT_CODE=1
 fi
+OUTPUT=$(git grep "check_output(" -- "*.py" | grep "universal_newlines=True" | grep -vE "encoding=.(ascii|utf8|utf-8).")
+if [[ ${OUTPUT} != "" ]]; then
+    echo "Python's check_output(...) seems to be used to get program outputs without explicitly"
+    echo "specifying encoding=\"utf8\":"
+    echo
+    echo "${OUTPUT}"
+    EXIT_CODE=1
+fi
 exit ${EXIT_CODE}