vcpkg bash completion mess up when in manifest mode

[linquize]

vcpkg bash completion mess up when in manifest mode. That is, vcpkg.json exists in the parent directory of vcpkg.

~/project$ touch vcpkg.json # Create vcpkg.json
~/project$ cd vcpkg
~/project/vcpkg$ . scripts/vcpkg_completion.bash # Enable bash completion
~/project/vcpkg$ ./vcpkg <tab><tab>

Expected Result:

cache      create     export     help       integrate  owns       search     upgrade
contact    edit       hash       install    list       remove     update     version

Actual Result:

Add                     feature                 packages
and                     `--feature-flags`       Pass
are                     `--feature-flags`.      ports
at                      flag                    README.md
bootstrap-vcpkg.bat     following:              README_zh_CN.md
bootstrap-vcpkg.sh      hash                    remove
buildtrees              help                    scripts
but                     /home/user/project,     search
cache                   If                      silence
can:                    install                 the
CHANGELOG.md            integrate               this
classic                 LICENSE.txt             to
comma-separated         list                    toolsrc
contact                 manifest                triplets
CONTRIBUTING.md         manifest-root           update
create                  `-manifests`            upgrade
detected                `manifests`             use
directory               manifests               variable
do                      may                     vcpkg
docs                    mode,                   `VCPKG_FEATURE_FLAGS`.
downloads               not                     version
edit                    NOTICE.txt              Warning:
enabled.                of                      wish
environment             one                     `--x-manifest-root`
error                   option.                 you
export                  owns                    your

[linquize]

https://github.com/microsoft/vcpkg/blob/385fb523320da4617966e34fcd586beecfcc9014/toolsrc/src/vcpkg/vcpkgpaths.cpp#L168-L193

Should not to output warning message if command is autocomplete