git send-email splits name with comma

Hi all,

If the name of an email address contains a comma, it will be split incorrectly into multiple addresses. A public example can be found at[1]. I originally say this with git 2.25.1, as packaged by my distro, but I could reproduce it with the latest version from git:

    $ git send-email  --to "foo bar, geert <geert@linux-m68k.org>"
/tmp/dummy.patch
    /tmp/dummy.patch
    (mbox) Adding cc: Geert Uytterhoeven <geert@linux-m68k.org> from
line 'From: Geert Uytterhoeven <geert@linux-m68k.org>'

    From: Geert Uytterhoeven <geert@linux-m68k.org>
    To: foo,
            bar,
            geert <geert@linux-m68k.org>
    Subject: [PATCH] dummy test
    Date: Mon,  4 Oct 2021 15:52:53 +0200
    Message-Id: <git-2.33.0.610.3.git.geert@linux-m68k.org
    X-Mailer: git-send-email 2.33.0.610.gcefe983a320c03d7
    MIME-Version: 1.0
    Content-Transfer-Encoding: 8bit

        The Cc list above has been expanded by additional
        addresses found in the patch commit message. By default
        send-email prompts before sending whenever this occurs.
        This behavior is controlled by the sendemail.confirm
        configuration setting.

        For additional information, run 'git send-email --help'.
        To retain the current behavior, but squelch this message,
        run 'git config --global sendemail.confirm auto'.

    Send this email? ([y]es|[n]o|[e]dit|[q]uit|[a]ll):
    OK. Log says:
    Sendmail: /usr/sbin/sendmail -i foo bar geert@linux-m68k.org
    From: Geert Uytterhoeven <geert@linux-m68k.org>
    To: foo,
            bar,
            geert <geert@linux-m68k.org>
    Subject: [PATCH] dummy test
    Date: Mon,  4 Oct 2021 15:52:53 +0200
    Message-Id: <git-2.33.0.610.3.git.geert@linux-m68k.org
    X-Mailer: git-send-email 2.33.0.610.gcefe983a320c03d7
    MIME-Version: 1.0
    Content-Transfer-Encoding: 8bit

    Result: OK

So "foo bar, geert <geert@linux-m68k.org>" is split in three parts, and /usr/sbin/sendmail (exim 4.93 in my case) will have sent the email to "foo" and "bar" (both extended with my local non-public domain) and "geert <geert@linux-m68k.org>".

Thanks!

[1] "Enrico Weigelt, metux IT consult <lkml@metux.net>" is split in 3 parts
    https://lore.kernel.org/linux-gpio/c987d0bf744150ca05bd952f5f9e5fb3244d27b0.1633350340.git.geert+renesas@glider.be/raw

Gr{oetje,eeting}s,

                        Geert