cd (using /bin/sh) may leave you in the wrong directory.

Fix: 

Don't blindly eliminate `..' in the target directory name by also 
eliminating the previous component. If the previous component was 
a symbolic link, the elimination might be bogus.
How-To-Repeat: 
Run the following shell script:

---
#!/bin/sh
cd /tmp
rm -rf /tmp/good /tmp/bad
mkdir good
mkdir good/some
mkdir good/etc
echo  "Test OK" > good/etc/FILE
mkdir bad
mkdir bad/etc
echo  "Test failed" > bad/etc/FILE
ln -s ../good/some bad/some
cd /tmp/bad/some/../etc
cat FILE
/bin/pwd
cd ..
/bin/pwd
cd /tmp
rm -rf /tmp/good /tmp/bad
---