Add fix for framework-mbed and python3.9

builder/frameworks/mbed.py

@@ -25,13 +25,37 @@ the mbed Developer Community.
 http://mbed.org/
 """
 
-from os.path import join
+import os
 
 from SCons.Script import Import, SConscript
 
 Import("env")
 
 
+def fixi():
+    """Fix intelhex compat issue in framework-mbed 5 with python3.9"""
+    compat = os.path.join(
+        env.PioPlatform().get_package_dir("framework-mbed"),
+        'platformio',
+        'package_deps',
+        'py3',
+        'intelhex',
+        'compat.py'
+    )
+    with open(compat) as fp:
+        content = fp.read()
+
+    if 'array_tobytes = getattr(array.array, "tobytes", array.array.tostring)' in content:
+        content = content.replace(
+            'array_tobytes = getattr(array.array, "tobytes", array.array.tostring)',
+            'array_tobytes = getattr(array.array, "tobytes", array.array.tobytes)',
+        )
+        with open(compat, 'w') as fp:
+            fp.write(content)
+
+fixi()
+
+
 def applymbedignore():
     import mbedignore
     mbedignorefile = env.subst('$PROJECT_DIR/.mbedignore')
@@ -40,7 +64,9 @@ def applymbedignore():
 
 
 applymbedignore()
+
+
 # https://github.com/platformio/builder-framework-mbed.git
 SConscript(
-    join(env.PioPlatform().get_package_dir("framework-mbed"), "platformio",
+    os.path.join(env.PioPlatform().get_package_dir("framework-mbed"), "platformio",
          "platformio-build.py"))