Error Displaying Help at REPL

## Platform details

Platform (macOS, Linux, Windows): Windows 10
Platform version: Windows 10 Home, Version 1703, OS Build 15063.674
JRE/JDK version (java -version): JRE: "1.8.0_141"

## Boot details

Boot version (2.7.1): 2.7.1
build.boot present? (yes/no): yes
~/.boot/profile present? (yes/no): no
Task name? (if applicable): any

This problem occurs for any task:

I execute this command at the boot REPL:
`(boot (jar :help true))`

I get the following returned with an error at the bottom:
```
Build a jar file for the project.

Options:
-h, --help Print this help info.
-f, --file PATH PATH sets the target jar file name.
-M, --manifest KEY=VAL Conj [KEY VAL] onto the jar manifest map.
-m, --main MAIN MAIN sets the namespace containing the -main function.
-p, --project SYM SYM sets the project symbol -- used to find the correct pom.xml file.
java.lang.IllegalArgumentException: Arguments must be either all strings or all fns
```