bug#36964: Some importer tests failing?

[Christopher Lemmer Webber]

A number of tests, including in cpan.scm, crate.scm, gem.scm are
failing for me.  Not sure if it's just me or not...

Some example output:

actual-value: #f
actual-error:
+ (wrong-type-arg
+   "string-prefix?"
+   "Wrong type argument in position ~A (expecting ~A): ~S"
+   (2 "string" #f)
+   (#f))
result: FAIL

;;; (fail #f #f)
actual-value: #f
result: FAIL

actual-value: #f
actual-error:
+ (wrong-type-arg
+   "string-prefix?"
+   "Wrong type argument in position ~A (expecting ~A): ~S"
+   (2 "string" #f)
+   (#f))
result: FAIL

I'm guessing something changed in the general importer code?