A WTF moment (see http://mattdenner.github.com/2010/02/27/a-wtf-moment.html)

exec.c

/*
 * Do a path search.  The variable path (passed by reference) should be
 * set to the start of the path before the first call; padvance will update
 * this value as it proceeds.  Successive calls to padvance will return
 * the possible path expansions in sequence.  If an option (indicated by
 * a percent sign) appears in the path entry then the global variable
 * pathopt will be set to point to it; otherwise pathopt will be set to
 * NULL.
 */

const char *pathopt;

char *
padvance(const char **path, const char *name)
{
	const char *p;
	char *q;
	const char *start;
	size_t len;

	if (*path == NULL)
		return NULL;
	start = *path;
	for (p = start ; *p && *p != ':' && *p != '%' ; p++);
	len = p - start + strlen(name) + 2;	/* "2" is for '/' and '\0' */
	while (stackblocksize() < len)
		growstackblock();
	q = stackblock();
	if (p != start) {
		memcpy(q, start, p - start);
		q += p - start;
		*q++ = '/';
	}
	strcpy(q, name);
	pathopt = NULL;
	if (*p == '%') {
		pathopt = ++p;
		while (*p && *p != ':')  p++;
	}
	if (*p == ':')
		*path = p + 1;
	else
		*path = NULL;
	return stalloc(len);
}

gistfile1.txt

$ rake metrics:all
(in /home/matt/brute_force_capatcha)
saikuro --filter_cyclo 0 --warn_cyclo 5 --error_cyclo 7 --output_directory tmp/metric_fu/scratch/saikuro --formater text --input_directory "lib" --cyclo  
sh: saikuro: not found
Saikuro failed with exit status: 127

gistfile2.txt

matt $ echo $PATH
/home/matt/.rvm/rubies/ruby-1.8.7-p249/bin:/home/matt/.rvm/gems/ruby-1.8.7-p249%image/bin:/home/matt/.rvm/gems/ruby-1.8.7-p249%global/bin:/home/matt/.rvm/bin:/home/matt/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/var/lib/gems/1.8/bin:~/bin
matt $ which saikuro
/home/matt/.rvm/gems/ruby-1.8.7-p249%global/bin/saikuro
matt $ saikuro --filter_cyclo 0 --warn_cyclo 5 --error_cyclo 7 --output_directory tmp/metric_fu/scratch/saikuro --formater text --input_directory "lib" --cyclo  
Parsing lib/live_sets_us/mini_magick_ext.rb
Parsing lib/live_sets_us/content_downloader.rb

Parsing lib/live_sets_us/template_image_extractor.rb
Parsing lib/live_sets_us/processor.rb
Parsing lib/live_sets_us.rb
matt $ which sh
/bin/sh
matt $ ls -l /bin/sh
lrwxrwxrwx 1 root root 9 2010-02-28 12:03 /bin/sh -> /bin/dash
matt $ sh
$ export PATH=/home/matt/.rvm/rubies/ruby-1.8.7-p249/bin:/home/matt/.rvm/gems/ruby-1.8.7-p249%image/bin:/home/matt/.rvm/gems/ruby-1.8.7-p249%global/bin:/home/matt/.rvm/bin:/home/matt/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/var/lib/gems/1.8/bin:~/bin
$ echo $PATH
/home/matt/.rvm/rubies/ruby-1.8.7-p249/bin:/home/matt/.rvm/gems/ruby-1.8.7-p249%image/bin:/home/matt/.rvm/gems/ruby-1.8.7-p249%global/bin:/home/matt/.rvm/bin:/home/matt/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/var/lib/gems/1.8/bin:~/bin
$ which saikuro
/home/matt/.rvm/gems/ruby-1.8.7-p249%global/bin/saikuro
$ saikuro
sh: saikuro: not found