Since commit ddf9069963 QEMU requires Python >= 3.5.

PEP 0394 [*] states that 'python3' should be available and
that 'python' is optional.

To avoid problem with unsupported versions, enforce the
shebang interpreter to Python 3.

[*] https://www.python.org/dev/peps/pep-0394/

Reported-by: John Snow <jsnow@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200130163232.10446-2-philmd@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 scripts/checkpatch.pl | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 3aef6e3dfe..ce43a306f8 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -1460,6 +1460,12 @@ sub process {
 			}
 		}
 
+# Only allow Python 3 interpreter
+		if ($realline == 1 &&
+			$line =~ /^\+#!\ *\/usr\/bin\/(?:env )?python$/) {
+			ERROR("please use python3 interpreter\n" . $herecurr);
+		}
+
 # Accept git diff extended headers as valid patches
 		if ($line =~ /^(?:rename|copy) (?:from|to) [\w\/\.\-]+\s*$/) {
 			$is_patch = 1;
-- 
2.21.1