Number with sign is read as octal despite a leading 10#

[Isaac Marcos]

Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64'
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-pc-linux-gnu'
-DCONF_VENDOR
uname output: Linux IO 4.9.0-6-amd64 #1 SMP Debian 4.9.88-1+deb9u1
(2018-05-07) x86_64 GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 4.4
Patch Level: 12
Release Status: release

Description:
A value inside an arithmetic expansion is processed as octal despite using
a 10# preffix.

Repeat-By:
        $ echo $((10#+0034))
        28

Fix:
        Extract optional sign before parsing the number, re-attach after.

-- 
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Best case, Worst case, and Just in case