.travis.yml: Check more Python scripts with pylint (#2019)

Use renamed pylintrc file that is only meant for Travis checks.

Check all Python scripts in 'addons', 'htmlreport' and 'tools'

Errors for `_socketobject` class are disabled, see
https://stackoverflow.com/questions/10300082/how-to-prevent-python-pylint-complaining-about-socket-class-sendall-method

Install imported modules `unittest2` and `pexpect` via pip.

Add "./addons" to search-path for modules because
"tools/compare-ast-clang-and-cppcheck.py" imports cppcheckdata.py from
addons. Pylint does not seem to evaluate
`sys.path.insert(0, '../addons')` in the script. So an `init-hook` is
necessary in pylintrc_travis.

.travis.yml

@@ -21,6 +21,8 @@ before_install:
  - travis_retry sudo apt-get install -qq python-pygments qt5-default qt5-qmake qtbase5-dev qtcreator libxml2-utils libpcre3 gdb unzip wx-common xmlstarlet
  - travis_retry sudo python2 -m pip install --upgrade pytest==4.6.4
  - travis_retry python2 -m pip install --user pylint
+ - travis_retry python2 -m pip install --user unittest2
+ - travis_retry python2 -m pip install --user pexpect
 
 matrix:
 # do notify immediately about it when a job of a build fails.
@@ -86,10 +88,10 @@ matrix:
         - python -m compileall ./addons
         - python3 -m compileall ./addons
 # run pylint
-        - cd addons
+#        - pylint --rcfile=pylintrc_travis addons/y2038/*.py ! First resolve https://trac.cppcheck.net/ticket/9210 "y2038 addon no longer working"
-#        - pylint *.py y2038/*.py ! First resolve https://trac.cppcheck.net/ticket/9210 "y2038 addon no longer working"
+        - pylint --rcfile=pylintrc_travis addons/*.py
-        - pylint *.py
+        - pylint --rcfile=pylintrc_travis htmlreport/*.py
-        - cd ..
+        - pylint --rcfile=pylintrc_travis tools/*.py
 # check python syntax by compiling some selected scripts
         - python -m py_compile ./tools/donate-cpu.py
         - python3 -m py_compile ./tools/donate-cpu.py

addons/pylintrc

@@ -1,5 +0,0 @@
-# Just the severe stuff...
-[MESSAGES CONTROL]
-disable=C,R,W
-[REPORTS]
-reports=no

pylintrc_travis

@@ -0,0 +1,10 @@
+# Just the severe stuff...
+[MESSAGES CONTROL]
+disable=C,R,W
+[REPORTS]
+reports=no
+[TYPECHECK]
+# See https://stackoverflow.com/questions/10300082/how-to-prevent-python-pylint-complaining-about-socket-class-sendall-method
+ignored-classes=SQLObject,_socketobject
+[MASTER]
+init-hook='import sys; sys.path.append("./addons")'

tools/daca2-download.py

@@ -84,6 +84,7 @@ def removeAll():
                     shutil.rmtree(filename, onerror=handleRemoveReadonly)
                 else:
                     os.remove(filename)
+        # pylint: disable=undefined-variable
         except WindowsError as err:
             time.sleep(30)
             if count == 0: