Makefile: give explicit failure message to user if dependencies aren't found

diff --git a/Makefile b/Makefile
index 15ac44081cbdfd39896f701e289f3eec2e323470..3923a7e6516653ad0116aa7bb88bd5b55319c8c8 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -107,7 +107,9 @@ endif
 
 check-deps:
        $(PP) \
-        $(PYTHON) -c 'import allmydata, zfec, foolscap, simplejson, nevow, OpenSSL'
+        $(PYTHON) -c 'import allmydata, zfec, foolscap, simplejson, nevow, OpenSSL' || \
+       echo "Not all of Tahoe's dependencies are in place.  Please see the README for help on installing dependencies." && \
+       exit 1
 
 .checked-deps:
        $(MAKE) check-deps