From 0806a631fde855aa7307a65c64218e1cf646a042 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fr=C3=A9d=C3=A9ric=20P=C3=A9ters?= <fpeters@entrouvert.com>
Date: Fri, 14 May 2021 11:32:47 +0200
Subject: [PATCH] misc: allow _ as first variable character (for legacy ezt
 compat) (#53987)

---
 wcs/qommon/substitution.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/wcs/qommon/substitution.py b/wcs/qommon/substitution.py
index d06ca95d0..b2bee529e 100644
--- a/wcs/qommon/substitution.py
+++ b/wcs/qommon/substitution.py
@@ -163,7 +163,7 @@ class CompatibilityNamesDict(dict):
     # custom dictionary that provides automatic fallback to legacy variable
     # names (namespaced with underscores)
 
-    valid_key_regex = re.compile(r'^[a-zA-Z][a-zA-Z0-9_]*$')
+    valid_key_regex = re.compile(r'^[a-zA-Z_][a-zA-Z0-9_]*$')
 
     def get(self, key, default=None):
         try: