I must be missing something here ... 

die "Not enough disk space.\n" unless check_disk_space;

[download]
... causes error ... 
Bareword "check_disk_space" not allowed while "strict subs" in use at 
+./thing line 60.
Execution of ./thing aborted due to compilation errors.

[download]
... but ... 
die "Not enough disk space.\n" if check_disk_space;

[download]
... does not.

Why?

In reply to unless weirdness by Plankton

Title:
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