fix escaping of backslash for bash 4.3

`"${PATH//\//\/}"` -- returns PATH var with all slashes `/` replaced with escaped slashes `\/` but in bash 4.3 it doesn't work as itended. FIx should works both in 4.3 and 4.2
Merge pull request #3029 from budnik/patch-1

Fix escaping of backslash for bash 4.3