Unexpected highlighting when function starts with pushd or popd

[alexr00]

The code with a problem is:

a() {
	pushd a
	popd
}

It looks like:

It should look like:

The p and the ushd should all be the same token and the same color.

The p has the following scopes:

meta.statement.shell
meta.function.body.shell
meta.function.shell
source.shell

The u, s, h, and d are all individual tokens and have the following scopes:

string.unquoted.shell
meta.statement.command.name.shell
meta.statement.command.shell
meta.statement.shell
meta.function.body.shell
meta.function.shell
source.shell

Original from @Salamandar in microsoft/vscode#228520