Fix pylint errors and warnings

Remove `except` block which immediately raises the same exception again (it's
not a subclass of another caught exception, so this is safe).

Remove a false positive, because it is not emitted from the code base.

Disable subprocess-popen-preexec-fn in startProgram, which is not used
internally.

src/bin/composer

@@ -23,9 +23,11 @@ log = logging.getLogger("composer")
 import os
 import sys
 
-from composer import vernum
-from composer.cli import main
-from composer.cli.cmdline import composer_cli_parser
+# Disable pylint warnings for these, because it cannot deal with this file and
+# the module both being called "composer"
+from composer import vernum                             # pylint: disable=import-self
+from composer.cli import main                           # pylint: disable=no-name-in-module
+from composer.cli.cmdline import composer_cli_parser    # pylint: disable=no-name-in-module
 
 VERSION = "{0}-{1}".format(os.path.basename(sys.argv[0]), vernum)
 

src/pylorax/executils.py

@@ -115,6 +115,7 @@ def startProgram(argv, root='/', stdin=None, stdout=subprocess.PIPE, stderr=subp
     if env_add:
         env.update(env_add)
 
+    # pylint: disable=subprocess-popen-preexec-fn
     return subprocess.Popen(argv,
                             stdin=stdin,
                             stdout=stdout,

src/pylorax/imgutils.py

@@ -196,10 +196,7 @@ def loop_attach(outfile):
 
             # Sometimes the loop device isn't ready yet, make extra sure before returning
             loop_waitfor(dev, outfile)
-        except CalledProcessError:
-            # Problems running losetup are always errors, raise immediately
-            raise
-        except RuntimeError as e:
+        except RuntimeError:
             # Try to setup the loop device 3 times
             if retries == 3:
                 logger.error("loop_attach failed, retries exhausted.")

src/pylorax/ltmpl.py

@@ -248,10 +248,10 @@ class LoraxTemplateRunner(object):
                 # skip the bit about "ltmpl.py, in _run()" - we know that
                 exclines.pop(1)
                 # log the "ErrorType: this is what happened" line
-                logger.error("  " + exclines[-1].strip())
+                logger.error("  %s", exclines[-1].strip())
                 # and log the entire traceback to the debug log
                 for _line in ''.join(exclines).splitlines():
-                    logger.debug("  " + _line)
+                    logger.debug("  %s", _line)
                 if self.fatalerrors:
                     raise
 

tests/pylint/runpylint.py

@@ -9,9 +9,6 @@ class LoraxLintConfig(PocketLintConfig):
         PocketLintConfig.__init__(self)
 
         self.falsePositives = [ FalsePositive(r"Module 'pylorax' has no 'version' member"),
-                                # threading.Lock() is a factory function which returns an
-                                # instance of the Lock class that is supported by the platform
-                                FalsePositive(r"Context manager 'lock' doesn't implement __enter__ and __exit__"),
                                 FalsePositive(r"Catching too general exception Exception"),
                                 FalsePositive(r"^E0712.*: Catching an exception which doesn't inherit from (Base|)Exception: GError$"),
                                 FalsePositive(r"Module 'composer' has no 'version' member"),