Also see Publishing websites with Jekyll, Apache and SVN
If you send console output via email (like, say the output of jekyll build as part of a SVN post-commit hook script) if there are ANSI control characters in the string (e.g. colour codes) this can break things. In this case the mail command (Debian 9 default exim) was only sending text up to the first ANSI code, which meant that the jekyll build error messages (which are yellow and red) were missing.
To fix this pipe the text through ansi2txt (comes with the colorized-logs package in Debian and Ubuntu). This strips out all ANSI control codes making the string email safe.
(After this I pipe it through unix2dos to convert to CRLF line endings, as this appears to be the standard for email. On Debian this comes with the dos2unix package.)
The last line in the hook script then becomes
echo "$LOGVAR" | /usr/bin/ansi2txt | /usr/bin/unix2dos | mail -s "$REPOS_BASENAME build $REV" "$BUILD_EMAIL"
