Add system's requirements.txt, enforce flake8 linter

Fix style issues in functional tests.

system/t11_package/show.py

@@ -1,12 +1,16 @@
 from lib import BaseTest
 
 
+def sortLines(_, s):
+    return "\n".join(sorted(s.split("\n")))
+
+
 class ShowPackage1Test(BaseTest):
     """
     show package: regular show
     """
     fixtureDB = True
-    outputMatchPrepare = lambda _, s: "\n".join(sorted(s.split("\n")))
+    outputMatchPrepare = sortLines
     runCmd = "aptly package show 'Name (% nginx-extras*)'"
 
 
@@ -22,7 +26,7 @@ class ShowPackage3Test(BaseTest):
     show package: by key
     """
     fixtureDB = True
-    outputMatchPrepare = lambda _, s: "\n".join(sorted(s.split("\n")))
+    outputMatchPrepare = sortLines
     runCmd = "aptly package show nginx-full_1.2.1-2.2+wheezy2_amd64"
 
 
@@ -31,7 +35,7 @@ class ShowPackage4Test(BaseTest):
     show package: with files
     """
     fixtureDB = True
-    outputMatchPrepare = lambda _, s: "\n".join(sorted(s.split("\n")))
+    outputMatchPrepare = sortLines
     gold_processor = BaseTest.expand_environ
     runCmd = "aptly package show -with-files nginx-full_1.2.1-2.2+wheezy2_amd64"
 
@@ -41,7 +45,7 @@ class ShowPackage5Test(BaseTest):
     show package: with inclusion
     """
     fixtureDB = True
-    outputMatchPrepare = lambda _, s: "\n".join(sorted(s.split("\n")))
+    outputMatchPrepare = sortLines
     runCmd = "aptly package show -with-references nginx-full_1.2.1-2.2+wheezy2_amd64"
 
 
@@ -58,7 +62,7 @@ class ShowPackage6Test(BaseTest):
         "aptly repo create repo1",
         "aptly repo import wheezy-main repo1 nginx",
     ]
-    outputMatchPrepare = lambda _, s: "\n".join(sorted(s.split("\n")))
+    outputMatchPrepare = sortLines
     runCmd = "aptly package show -with-references nginx-full_1.2.1-2.2+wheezy2_amd64"
 
 
@@ -72,5 +76,5 @@ class ShowPackage7Test(BaseTest):
         "aptly repo add a ${files}",
         "aptly repo add b ${testfiles}"
     ]
-    outputMatchPrepare = lambda _, s: "\n".join(sorted(s.split("\n")))
+    outputMatchPrepare = sortLines
     runCmd = "aptly package show -with-references \"pyspi (0.6.1-1.3)\""