Revert "[wip] Fix how vcs_relative_path first resolves an absolute path"

This reverts commit a7fd514569.

Sadly this doesn't work in all cases (if the file doesn't exist) and
fails on MacOS (I think).

bin/_blackbox_common.sh

@@ -366,22 +366,13 @@ function enumerate_blackbox_repos() {
   done
 }
 
-# Resolve the absolute path of a relative one
-# Adapted from https://unix.stackexchange.com/a/483514
-function abs() {
-  local _pwd bn
-  [ -d "${1}" ] && _pwd="${1}"
-  [ -f "${1}" ] && { _pwd=$(dirname "${1}") ;  bn=/$(basename "${1}") ;}
-  pushd "$_pwd" >/dev/null || exit
-  echo "$(pwd)${bn}"
-  popd >/dev/null || exit
-}
-
 # Output the path of a file relative to the repo base
 function vcs_relative_path() {
-  local name
-  name=$(abs "$1")
-  name="${name#$REPOBASE}"
+  # Usage: vcs_relative_path file
+  local name="$1"
+  #python -c 'import os ; print(os.path.relpath("'"$(pwd -P)"'/'"$name"'", "'"$REPOBASE"'"))'
+  local p=$( printf "%s" "$( pwd -P )/${1}" | sed 's#//*#/#g' )
+  local name="${p#$REPOBASE}"
   name=$( printf "%s" "$name" | sed 's#^/##g' | sed 's#/$##g' )
   printf "%s" "$name"
 }