Local import and regex in external configuration

[Naeoth]

• Rollup Version: 2.28.2
• Operating System (or Browser): MacOS (10.15.7)
• Node Version (if applicable): 14.8.0
• Link to reproduction (IMPORTANT, read below): https://github.com/Naeoth/rollup-issue

To avoid unresolved dependencies warning on compilation, I use a regex for the external rollup configuration to exclude all the imports which starts with "." (it means all the local import in fact).
It worked perfectly before 2.26.8 but a change in 2.26.8 broke the trick.
It seems that now, it's impossible to exclude the local import with a regex if you have a least a regex with /.+/ or /.*/.

Expected Behavior

Include the import like "./..." in the bundle with the regex in the external.

Actual Behavior

Treat the import like "./..." as external module with the regex in the external.

[lukastaegert]

Is this the same as #3811 ?