.gitignore is ignoring other directories with the same name

Question

From the docs for Git Ignore

A leading slash matches the beginning of the pathname. For example, /*.c matches cat-file.c but not mozilla-sha1/sha1.c.

Try changing vendor/ to /vendor/

From Git - gitignore Documentation:

"If the pattern ends with a slash, it is removed for the purpose of the following description, but it would only find a match with a directory. In other words, foo/ will match a directory foo and paths underneath it, but will not match a regular file or a symbolic link foo (this is consistent with the way how pathspec works in general in Git)."

"If the pattern does not contain a slash /, Git treats it as a shell glob pattern and checks for a match against the pathname relative to the location of the .gitignore file (relative to the toplevel of the work tree if not from a .gitignore file)."

Simply remove the /

.idea 
bin 
vendor 
composer.lock 
composer.phar