If grep is set to search in all files under each directory recursively (-r) but
to exclude certain directories (–exclude-dir=foo), then grep crashes with a
segmentation fault. When grepdir computes the name_space (src/grep.c:1361), it
calls function isdir1 via function savedir (lib/savedir.c:123). Now, the code
in isdir1 that is supposed to remove the trailing slashes from the directory
name uses the uninitialized variable path instead of variable dir
(lib/savedir.c:51). The nullpointer dereference results in a segmentation
fault.


Example of Correct Fix: 
Substitute path with dir. 

Examples of Incorrect Fixes: 
1) Return if path is not initialized (Regression because isdir1 returns false
even if dir is a directory). 

2) Only use path if initialized (Regression because isdir1 does not remove
trailing slashes).
