Upgrade flake8 to 3.7.9.

Have to use no-build-isolation option for pip on a few integration tests
because flake8-3.7.x depends on entrypoints that require flit in a
build_system section of the toml file. We don't need that since we
already have a package with flit-built setup.py. In future release of
flake8 entrypoints are replaced with importlib-metadata, so this
dependency will not cause us issues any more, but the no-build-isolation
setting should be fine in the tests even in that case.

Author: zvezdan

pivy-importer/build.gradle

@@ -52,7 +52,7 @@ task importRequiredDependencies(type: JavaExec) { task ->
         'sphinx_rtd_theme:0.1.0=sphinx_rtd_theme:0.1.1',      // candidate for removal
     ].join(",")
     def packagesToInclude = [
-        'flake8:3.6.0',
+        'flake8:3.7.9',
         'Flask:0.12.2',
         'pbr:5.1.1',
         'pex:1.5.2',

pygradle-plugin/src/integTest/groovy/com/linkedin/gradle/python/plugin/FailureReasonProviderIntegrationTest.groovy

@@ -34,6 +34,14 @@ class FailureReasonProviderIntegrationTest extends Specification {
         | plugins {
         |     id 'com.linkedin.python-pex'
         | }
+        !
+        | python{
+        |     pipConfig = [:]
+        |     for (String command : ['install', 'wheel', 'download']) {
+        |         pipConfig.put(command, [:])
+        |         pipConfig.get(command).put('no-build-isolation', 'false')
+        |     }
+        | }
         |
         | configurations {
         |    testProj

pygradle-plugin/src/integTest/groovy/com/linkedin/gradle/python/plugin/ParallelWheelsIntegrationTest.groovy

@@ -45,9 +45,14 @@ class ParallelWheelsIntegrationTest extends Specification {
         | apply plugin: com.linkedin.gradle.python.plugin.WheelFirstPlugin
         | version = '1.0.0'
         | python {
-        |   pex {
-        |     fatPex = false
-        |   }
+        |     pex {
+        |         fatPex = false
+        |     }
+        |     pipConfig = [:]
+        |     for (String command : ['install', 'wheel', 'download']) {
+        |         pipConfig.put(command, [:])
+        |         pipConfig.get(command).put('no-build-isolation', 'false')
+        |     }
         | }
         | ${ PyGradleTestBuilder.createRepoClosure() }
         """.stripMargin().stripIndent()
@@ -104,6 +109,13 @@ class ParallelWheelsIntegrationTest extends Specification {
         | apply plugin: com.linkedin.gradle.python.plugin.WheelFirstPlugin
         |
         | version = '1.0.0'
+        | python {
+        |     pipConfig = [:]
+        |     for (String command : ['install', 'wheel', 'download']) {
+        |         pipConfig.put(command, [:])
+        |         pipConfig.get(command).put('no-build-isolation', 'false')
+        |     }
+        | }
         | ${ PyGradleTestBuilder.createRepoClosure() }
         """.stripMargin().stripIndent()
 

pygradle-plugin/src/main/groovy/com/linkedin/gradle/python/PythonExtension.groovy

@@ -65,7 +65,7 @@ class PythonExtension {
 
     /** A way to define forced versions of libraries */
     public Map<String, Map<String, String>> forcedVersions = [
-        'flake8'        : ['group': 'pypi', 'name': 'flake8', 'version': '3.6.0'],
+        'flake8'        : ['group': 'pypi', 'name': 'flake8', 'version': '3.7.9'],
         'pex'           : ['group': 'pypi', 'name': 'pex', 'version': '1.5.2'],
         'pip'           : ['group': 'pypi', 'name': 'pip', 'version': '18.1'],
         'pytest'        : ['group': 'pypi', 'name': 'pytest', 'version': '3.10.0'],