Issue #2666: Handle BROWSER environment variable properly for unknown browser names in the webbrowser module.
diff --git a/Lib/webbrowser.py b/Lib/webbrowser.py
index bfd353a..74f0270 100644
--- a/Lib/webbrowser.py
+++ b/Lib/webbrowser.py
@@ -625,7 +625,9 @@
# and prepend to _tryorder
for cmdline in _userchoices:
if cmdline != '':
- _synthesize(cmdline, -1)
+ cmd = _synthesize(cmdline, -1)
+ if cmd[1] is None:
+ register(cmdline, None, GenericBrowser(cmdline), -1)
cmdline = None # to make del work if _userchoices was empty
del cmdline
del _userchoices