Bug#870617: biber: deprecated regex warning

[Raphaël Bleuse <raphael.bleuse@imag.fr>]

Package: biber
Version: 2.7-2
Severity: normal

Dear Maintainer,

when using biber to generate a bibliography, the following warning is displayed
by the perl interpreter:

```
Unescaped left brace in regex is deprecated here (and will be fatal in Perl 5.30), passed through in regex; marked by <-- HERE in m/}(\pM+\pL){ <-- HERE (?!\pL+\\)/ at /usr/share/perl5/Biber/LaTeX/Recode.pm line 316, <DATA> line 1.
```

Steps to reproduce:

```
$ pdflatex bug
$ biber bug
```

I expect the regex to be fixed (I'm not a perl guru…)

Raphaël

-- System Information:
Debian Release: buster/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 4.11.0-1-amd64 (SMP w/8 CPU cores)
Locale: LANG=fr_FR.UTF-8, LC_CTYPE=fr_FR.UTF-8 (charmap=UTF-8), LANGUAGE=fr_FR.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages biber depends on:
ii  libautovivification-perl                     0.16-1+b4
ii  libbusiness-isbn-perl                        3.003-1
ii  libbusiness-ismn-perl                        1.131-1
ii  libbusiness-issn-perl                        1.002-1
ii  libclass-accessor-perl                       0.34-1
ii  libdata-compare-perl                         1.25-0.1
ii  libdata-dump-perl                            1.23-1
ii  libdata-uniqid-perl                          0.12-1
ii  libdate-simple-perl                          3.0300-1+b5
ii  libdatetime-calendar-julian-perl             0.04-1
ii  libdatetime-format-builder-perl              0.8100-1
ii  libdatetime-perl                             2:1.42-1+b2
ii  libencode-eucjpms-perl                       0.07-3+b6
ii  libencode-hanextra-perl                      0.23-4+b4
ii  libencode-jis2k-perl                         0.03-1+b4
ii  libfile-slurp-unicode-perl                   0.7.1-2
ii  libipc-run3-perl                             0.048-1
ii  liblist-allutils-perl                        0.12-1
ii  liblist-moreutils-perl                       0.416-1+b3
ii  liblog-log4perl-perl                         1.48-1
ii  liblwp-protocol-https-perl                   6.07-1
ii  libreadonly-perl                             2.050-1
ii  libregexp-common-perl                        2017060201-1
ii  libsort-key-perl                             1.33-1+b5
ii  libtext-bibtex-perl                          0.80-1+b1
ii  libtext-csv-perl                             1.33-2
ii  libtext-csv-xs-perl                          1.26-1+b1
ii  libtext-roman-perl                           3.5-1
ii  libunicode-collate-perl                      1.19-1+b2
ii  libunicode-linebreak-perl                    0.0.20160702-1+b3
ii  liburi-perl                                  1.71-1
ii  libwww-perl                                  6.15-1
ii  libxml-libxml-simple-perl                    0.97-1
ii  libxml-libxslt-perl                          1.95-1+b2
ii  libxml-writer-perl                           0.625-1
ii  perl                                         5.26.0-4
ii  perl-modules-5.24 [libunicode-collate-perl]  5.24.1-7
ii  perl-modules-5.26 [libunicode-collate-perl]  5.26.0-4
ii  tex-common                                   6.07

Versions of packages biber recommends:
ii  texlive-bibtex-extra  2017.20170724-1

biber suggests no packages.

-- no debconf information

\documentclass{article}
\usepackage{biblatex}
\bibliography{biblio}
\begin{document}
\nocite{*}
\printbibliography
\end{document}

@article{HilbertD1891Ueber,
  author    = {Hilbert, David},
  title     = {{U}eber die stetige {A}bbildung einer {L}ine auf ein
               {F}l{\"a}chenst{\"u}ck},
  journal   = {Mathematische Annalen},
  volume    = 38,
  number    = 3,
  pages     = {459--460},
  year      = 1891,
  month     = sep,
  doi       = {10.1007/BF01199431},
  issn      = {1432-1807},
}