For the auto-mode-alist regexp "\\.tiarra-conf$" it's usual to make the
pattern instead something like

    "\\.tiarra-conf\\'"

to match only at end-of-string not at a newline.  Filenames ought not
contain newlines, but just in case.

We believe that the bug you reported is fixed in the latest version of
tiarra, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 710553@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Hideki Yamane <henrich@debian.org> (supplier of updated tiarra package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
Format: 1.8
Date: Sun, 04 Jan 2015 16:53:42 +0900
Source: tiarra
Binary: tiarra tiarra-conf-el
Architecture: source all
Version: 20100212-5
Distribution: unstable
Urgency: medium
Maintainer: Hideki Yamane <henrich@debian.org>
Changed-By: Hideki Yamane <henrich@debian.org>
Description:
 tiarra     - IRC proxy, stationing, logger and bot program (pirc)
 tiarra-conf-el - edit mode for tiarra.conf
Closes: 710549 710553
Changes:
 tiarra (20100212-5) unstable; urgency=medium
 .
   * debian/control
     - set Standards-Version: 3.9.6
     - fix Vcs-Browser
     - use "Depends: emacs" instead of specific Emacs version
   * debian/wrapper
     - rename "tiarra.wrapper -> tiarra"
     - rename "make-password.wrapper -> make-passwd.tiarra"
   * simplify debian/rules
   * debian/tiarra-conf-el.emacsen-startup
     - fix "M-x tiarra-conf-mode autoload error" (Closes: #710549)
       Thanks to Kevin Ryde <user42_kevin@yahoo.com.au>
     - fix "auto-mode-alist regexp \\'" (Closes: #710553)
       Thanks again, Kevin Ryde <user42_kevin@yahoo.com.au>
Checksums-Sha1:
 2042421782569896c562f32df58795d334c7256a 1853 tiarra_20100212-5.dsc
 c44de78316c6b0c8183de6dbbe0ece8abca735eb 5248 tiarra_20100212-5.debian.tar.xz
 bd8b52894b272863a4048dd138e03c1466b6b7f4 291286 tiarra_20100212-5_all.deb
 3e0afad82819e02aa31693c808ebec1c6a0c37a4 33668 tiarra-conf-el_20100212-5_all.deb
Checksums-Sha256:
 daf5098c7c8b1df438856a87a1cc17dc20fbd6277c531eace877ba268052dc97 1853 tiarra_20100212-5.dsc
 cb1db9da9c0d341c3b6e8c1a9d78c1cbb53ac02880e761e24b4f974e523d9808 5248 tiarra_20100212-5.debian.tar.xz
 81b4c1bf6bcd677d99db9635730b1ddd40af2bb5897012a3f48ca4dd457ef7d0 291286 tiarra_20100212-5_all.deb
 2bfd75fc923d299f61282db562dd633ad777ba3034a3516d451ca55fd0cd9ee1 33668 tiarra-conf-el_20100212-5_all.deb
Files:
 bd7fbd3bf9f7d57476b8f541bcc07fae 1853 net optional tiarra_20100212-5.dsc
 42c89d4221c4dbc8641395795136f51b 5248 net optional tiarra_20100212-5.debian.tar.xz
 886d28c8a2423b10a26fad212b71c569 291286 net optional tiarra_20100212-5_all.deb
 3966a078321cdbd4d259c8d2277e67f3 33668 lisp optional tiarra-conf-el_20100212-5_all.deb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=rZJB
-----END PGP SIGNATURE-----

reopen 710553
thanks

Running

    emacs -q foo.tiarra-conf
    =>
    File mode specification error: (invalid-regexp "Trailing backslash")

Where /etc/emacs/site-start.d/50tiarra-conf-el.el has

    "\\.tiarra-conf\\"

I believe it should be

    "\\.tiarra-conf\\'"