...curl works, wget works
Hmmm, one/both of the above is/are self-evidently not true - look at the error returned from the OS during the rename:
Error while trying to rename '/Users/me/.cpan/sources/authors/01mailrc
+.txt.gz.tmp604' to '/Users/me/.cpan/sources/authors/01mailrc.txt.gz':
+ No such file or directory
That shouts loudly (to me anyway) that the download of /Users/me/.cpan/sources/authors/01mailrc.txt.gz.tmp604
failed ... quietly.
A user level that continues to overstate my experience :-))