Bug#1067874: Allow trailing whitespace in apt patterns

[Trent W. Buck]

Package: apt
Version: 2.7.14
Severity: wishlist

I think this is a bug:

    root@hera:/# apt list '?source-package(^mg$) '
    Listing... Error!
    E: input:21-22: error: Expected end of file
       ?source-package(^mg$)
                            ^

I think apt should ignore trailing whitespace, just as it ignores leading 
whitespace.

Here is a more complete transcript:

    bash5$ mmdebstrap bookworm /dev/null --quiet --customize-hook='chroot $1'
    root@hera:/# dpkg-query -W apt
    apt 2.6.1
    root@hera:/# apt --version
    apt 2.6.1 (amd64)
    root@hera:/# apt list '?source-package(^mg$)'
    Listing... Done
    mg/stable 20221112-1 amd64
    root@hera:/# apt list ' ?source-package(^mg$)'
    Listing... Done
    mg/stable 20221112-1 amd64
    root@hera:/# apt list ' ?source-package(^mg$) '
    Listing... Error!
    E: input:22-23: error: Expected end of file
        ?source-package(^mg$) 
                             ^

And again in sid:

    bash5$ mmdebstrap sid /dev/null --quiet --customize-hook='chroot $1'
    root@hera:/# dpkg-query -W apt
    apt 2.7.14
    root@hera:/# apt --version
    apt 2.7.14 (amd64)
    root@hera:/# apt list '?source-package(^mg$)'
    Listing... Done
    mg/unstable 20230501-1 amd64
    root@hera:/# apt list ' ?source-package(^mg$)'
    Listing... Done
    mg/unstable 20230501-1 amd64
    root@hera:/# apt list ' ?source-package(^mg$) '
    Listing... Error!
    E: input:22-23: error: Expected end of file
        ?source-package(^mg$) 
                             ^