Empty strings unexpectedly interpolate as no value

[AdaCohenGremlin]

For example:

shellEscapeTag`echo 'hello' | grep ${pattern}`

If pattern is an empty string, this will turn into the string "echo 'hello' | grep "

Executing that will cause grep to error, because the shell interprets it as no argument. It seems like the expected behavior would be to call grep with an empty string argument, i.e. "echo 'hello' | grep ''"