change default for minVirtualenvVersion to 16 to avoid fails on environments created with the previous plugin versions

Author: xvik

CHANGELOG.md

@@ -1,10 +1,10 @@
 * Support python installation from Windows Store (#14)
-* Changed virtualenv version used by default from 16.7.9 to 20.4.2
+* Changed virtualenv version installed by default from 16.7.9 to 20.4.2
   (because only recent versions could work correctly with python installed from Windows Store)
-* Add minimal required virtualenv check: by defautl it's virtualenv 20.0.11 (compatible with Windows Store python)
-  Configured with python.minVirtualenvVersion. Important because v20 changes pip installation
-    strategy in environment to the same version as bundled with virtualenv instead of always
-    downloading new pip (extremely important for python 2 support because pip 21 does not support it anymore)
+* Add minimal required virtualenv check: by defautl it's virtualenv 16 (to not fail previously working environments). 
+  But it is recommended to use at least 20.0.11 (compatible with Windows Store python). V20 changes pip installation
+  strategy in environment to the same version as bundled with virtualenv instead of always downloading new pip (which increase builds stability).
+  Configured with python.minVirtualenvVersion. 
 * Fix up-to-date check in pipInstall task for VCS modules (the latest pip changed freeze output syntax)
 * Hide passwords in logs for pip extra index repository urls with credentials (extraIndexUrls config) (#12)
 * Add general logged command cleaning mechanism to Python object for plugin authors (Pip object uses it for passwords hiding)

src/main/groovy/ru/vyarus/gradle/plugin/python/PythonExtension.groovy

@@ -121,17 +121,17 @@ class PythonExtension {
      */
     String virtualenvVersion = '20.4.2'
     /**
-     * Minimal required virtualenv version. It is important to use virtualenv 20 instead of 16 or older because
+     * Minimal required virtualenv version. It is recommended to use virtualenv 20 instead of 16 or older because
      * it was a complete rewrite (and now it is stable enough). The most important moment is pip installation
-     * behaviour: virtualenv <=15  was always downloading the latest pip which compromise build stability.
-     * Moreover, pip 21 drops python 2 support, so using old virtualenv with it would always lead to
-     * unusable environment.
+     * behaviour: virtualenv <=16  was always downloading the latest pip which compromise build stability.
      * <p>
-     * Used exact version 20.0.11 because it fixes Windows Store compatibility
-     * (https://github.com/pypa/virtualenv/issues/1709). But specified version could actually have any precision:
-     * e.g. '20' or '20.1'.
+     * Default value set to 16 to not fail environments, created with the previous plugin versions. But it
+     * is recommended to use at least 20.0.11 (because this version fixes Windows Store compatibility
+     * (https://github.com/pypa/virtualenv/issues/1709)). Older virtualenvs could also be used!
+     * <p>
+     * Specified version could actually have any precision: '20', '20.1', etc.
      */
-    String minVirtualenvVersion = '20.0.11'
+    String minVirtualenvVersion = '16'
     /**
      * Virtual environment path to use. Used only when {@link #scope} is configured to use virtualenv.
      * Virtualenv will be created automatically if not yet exists.