# Revert 6700a8dfaeb1e303955acc05dabd245b9ae3c97e

Bug 1622963 - Require python 3.6 for the build system. r=firefox-build-system-reviewers,rstewart

Differential Revision: https://phabricator.services.mozilla.com/D77754

diff -r 81f3a9d8e5f4 build/moz.configure/init.configure
--- a/build/moz.configure/init.configure	Tue Nov 17 21:27:44 2020 +0000
+++ b/build/moz.configure/init.configure	Wed Nov 18 08:22:17 2020 +0100
@@ -216,7 +216,7 @@
 # Python 3
 # ========
 
-option(env="PYTHON3", nargs=1, help="Python 3 interpreter (3.6 or later)")
+option(env="PYTHON3", nargs=1, help="Python 3 interpreter (3.5 or later)")
 
 option(
     env="VIRTUALENV_NAME",
@@ -327,7 +327,7 @@
             )
     else:
         # Fall back to the search routine.
-        python, version = find_python3_executable(min_version="3.6.0")
+        python, version = find_python3_executable(min_version="3.5.0")
 
         # The API returns a bytes whereas everything in configure is unicode.
         if python:
@@ -335,15 +335,15 @@
 
     if not python:
         raise FatalCheckError(
-            "Python 3.6 or newer is required to build. "
+            "Python 3.5 or newer is required to build. "
             "Ensure a `python3.x` executable is in your "
             "PATH or define PYTHON3 to point to a Python "
-            "3.6 executable."
+            "3.5 executable."
         )
 
-    if version < (3, 6, 0):
+    if version < (3, 5, 0):
         raise FatalCheckError(
-            "Python 3.6 or newer is required to build; "
+            "Python 3.5 or newer is required to build; "
             "%s is Python %d.%d" % (python, version[0], version[1])
         )
 
diff -r 81f3a9d8e5f4 python/mozbuild/mozbuild/pythonutil.py
--- a/python/mozbuild/mozbuild/pythonutil.py	Tue Nov 17 21:27:44 2020 +0000
+++ b/python/mozbuild/mozbuild/pythonutil.py	Wed Nov 18 08:22:17 2020 +0100
@@ -44,7 +44,7 @@
 def _find_python_executable(major):
     if major not in (2, 3):
         raise ValueError("Expected a Python major version of 2 or 3")
-    min_versions = {2: "2.7.0", 3: "3.6.0"}
+    min_versions = {2: "2.7.0", 3: "3.5.0"}
 
     def ret(min_version=min_versions[major]):
         from mozfile import which
diff -r 81f3a9d8e5f4 python/mozbuild/mozbuild/virtualenv.py
--- a/python/mozbuild/mozbuild/virtualenv.py	Tue Nov 17 21:27:44 2020 +0000
+++ b/python/mozbuild/mozbuild/virtualenv.py	Wed Nov 18 08:22:17 2020 +0100
@@ -691,7 +691,7 @@
     major, minor, micro = sys.version_info[:3]
     minimum_python_versions = {
         2: LooseVersion("2.7.3"),
-        3: LooseVersion("3.6.0"),
+        3: LooseVersion("3.5.0"),
     }
     our = LooseVersion("%d.%d.%d" % (major, minor, micro))