run-tests.sh fails when run in emacs shell (trivial patch included)

[chaw]

Running run-tests.sh in an emacs shell buffer fails with an odd message. I believe the problem is caused by the EMACS environment variable being set to 't' in emacs shells. The following patch seems to fix things.

--- a/run-tests.sh
+++ b/run-tests.sh
@@ -1,6 +1,6 @@
 #!/bin/sh
 
-if [ -z ${EMACS} ]; then
+if [ -z ${EMACS} -o ! -x ${EMACS} ]; then
    if [ -x "/Applications/Emacs.app/Contents/MacOS/Emacs" ]; then``
        EMACS="/Applications/Emacs.app/Contents/MacOS/Emacs"
    else