Turns out it was my GREP_OPTIONS environment variable. I had this in my .bashrc 
export GREP_OPTIONS="--exclude-from ~/.grep_excludes --color"
Seems some files were accidentally matching my excludes rules and the color was throwing off something else. Removing that fixed everything up (except for a single failure in t/porting/exec-bit.t).

In reply to Re^3: Can't install a modern Perl from source by mpeters
in thread Can't install a modern Perl from source by mpeters

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