Fix py3 version changed even version control enabled issue (#6422)

* Fix py3 version changed even version control enabled issue

* Add some comments and simplify the script

* Add the comment to explain how to get the not hooked command

Author: xumia

src/sonic-build-hooks/scripts/buildinfo_base.sh

@@ -22,15 +22,20 @@ log_err()
     echo "$1" 1>&2
 }
 
+# Get the real command not hooked by sonic-build-hook package
 get_command()
 {
-    local path=$(echo $PATH | sed 's#[^:]*buildinfo/scripts:##' | sed "s#/usr/sbin:##")
+    # Change the PATH env to get the real command by excluding the command in the hooked folders
+    local path=$(echo $PATH | sed 's#[^:]*buildinfo/scripts:##' | sed "s#/usr/local/sbin:##")
     local command=$(PATH=$path which $1)
     echo $command
 }
 
 check_version_control()
 {
+    # The env variable SONIC_VERSION_CONTROL_COMPONENTS examples:
+    # all            -- match all components
+    # py2,py3,deb    -- match py2, py3 and deb only
     if [[ ",$SONIC_VERSION_CONTROL_COMPONENTS," == *,all,* ]] || [[ ",$SONIC_VERSION_CONTROL_COMPONENTS," == *,$1,* ]]; then
         echo "y"
     else

src/sonic-build-hooks/scripts/symlink_build_hooks

@@ -1,7 +1,7 @@
 #!/bin/bash
 
 HOOK_PATH=/usr/local/share/buildinfo/hooks
-TARGET_PATH=/usr/sbin
+TARGET_PATH=/usr/local/sbin
 FILES=$(ls $HOOK_PATH)
 
 usage()