Enable Travis checking for two Python linting rules we are currently not violating

contrib/devtools/lint-python.sh

@@ -6,11 +6,13 @@
 #
 # Check for specified flake8 warnings in python files.
 
+# E101 indentation contains mixed spaces and tabs
 # E112 expected an indented block
 # E113 unexpected indentation
 # E115 expected an indented block (comment)
 # E116 unexpected indentation (comment)
 # E125 continuation line with same indent as next logical line
+# E129 visually indented line with same indent as next logical line
 # E131 continuation line unaligned for hanging indent
 # E133 closing bracket is missing indentation
 # E223 tab before operator
@@ -73,4 +75,4 @@
 # W605 invalid escape sequence "x"
 # W606 'async' and 'await' are reserved keywords starting with Python 3.7
 
-flake8 --ignore=B,C,E,F,I,N,W --select=E112,E113,E115,E116,E125,E131,E133,E223,E224,E242,E266,E271,E272,E273,E274,E275,E304,E306,E401,E402,E502,E701,E702,E703,E714,E721,E741,E742,E743,F401,E901,E902,F402,F404,F406,F407,F601,F602,F621,F622,F631,F701,F702,F703,F704,F705,F706,F707,F811,F812,F821,F822,F823,F831,F841,W191,W291,W292,W293,W504,W601,W602,W603,W604,W605,W606 .
+flake8 --ignore=B,C,E,F,I,N,W --select=E101,E112,E113,E115,E116,E125,E129,E131,E133,E223,E224,E242,E266,E271,E272,E273,E274,E275,E304,E306,E401,E402,E502,E701,E702,E703,E714,E721,E741,E742,E743,F401,E901,E902,F402,F404,F406,F407,F601,F602,F621,F622,F631,F701,F702,F703,F704,F705,F706,F707,F811,F812,F821,F822,F823,F831,F841,W191,W291,W292,W293,W504,W601,W602,W603,W604,W605,W606 .