FIGNORE not effective if it contains a full filename

[Josh Triplett]

Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS: -g -O2 -fdebug-prefix-map=/build/bash-vu7ylu/bash-5.0=. 
-fstack-protector-strong -Wformat -Werror=format-security -Wall 
-Wno-parentheses -Wno-format-security
uname output: Linux s 5.7.0-2-amd64 #1 SMP Debian 5.7.10-1 (2020-07-26) x86_64 
GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 5.0
Patch Level: 18
Release Status: release

Description:
        If FIGNORE contains the complete filename of a file, tab
        completion will not ignore it.

Repeat-By:
        First, `touch Cargo.{toml,lock}` to create a pair of files with a
        common prefix. (These two names commonly appear side-by-side in Rust
        projects, and you almost always want to tab-complete Cargo.toml, not
        Cargo.lock.)

        To test the baseline behavior, type `echo C` and press tab; bash
        will complete "Cargo." and wait for more input.

        Set FIGNORE=lock and try again; bash ignores Cargo.lock and
        completes Cargo.toml.

        Set FIGNORE=argo.lock and try again; bash again ignores
        Cargo.lock and completes Cargo.toml.

        Set FIGNORE=Cargo.lock and try again; bash just completes
        "Cargo." and waits for more input.