Python: wrapPythonPrograms: only wrap in $out/bin

Thus far all executables in a derivation were wrapped. This commit
only wraps executables in $out/bin. If other scripts need to be wrapped
as well, then one can use wrapPythonProgramsIn.

pkgs/development/interpreters/python/wrap.sh

@@ -1,7 +1,7 @@
 # Wrapper around wrapPythonProgramsIn, below. The $pythonPath
 # variable is passed in from the buildPythonPackage function.
 wrapPythonPrograms() {
-    wrapPythonProgramsIn $out "$out $pythonPath"
+    wrapPythonProgramsIn "$out/bin" "$out $pythonPath"
 }
 
 # Builds environment variables like PYTHONPATH and PATH walking through closure
@@ -47,6 +47,7 @@ wrapPythonProgramsIn() {
     buildPythonPath "$pythonPath"
 
     # Find all regular files in the output directory that are executable.
+    if [ -d "$dir" ]; then
         find "$dir" -type f -perm -0100 -print0 | while read -d "" f; do
             # Rewrite "#! .../env python" to "#! /nix/store/.../python".
             # Strip suffix, like "3" or "2.7m" -- we don't have any choice on which
@@ -75,6 +76,7 @@ wrapPythonProgramsIn() {
                 fi
             fi
         done
+    fi
 }
 
 # Adds the lib and bin directories to the PYTHONPATH and PATH variables,