Submitting your vote...
While I was writing "Extended domains" extension, I thought that I should disable access to third-party IDNA library that I use. It is generally good not to allow anyone to access directly anything what they should not access. So I added a simple .htaccess file to the directory above IDNA library:
<IfModule mod_access.c>
deny from all
</IfModule>
I uploaded extension and looked into TER. And I realized that my .htaccess is not there. So I went looking into Extension Manager (EM) and discovered that EM by default disallows uploading of files whose names start from a dot. Fortunately there is a regular expression that control this behavior, so I "tuned" it to allow uploading of .htaccess. Here is this regular expression:
(CVS|\.(?!htaccess$).*|.*~|.*\.bak)
If you wish to use it, you need to go to Install tool and search for "excludeForPackaging" setting there. Put this new regular expression and you can upload .htaccess files and make your extensions more secure.
