add beta Pypy support

bin/compile

@@ -58,6 +58,8 @@ PY36="python-3.6"
 PY35="python-3.5"
 PY34="python-3.4"
 PY27="python-2.7"
+PYPY27="pypy2.7"
+PYPY36="pypy3.6"
 
 # Which stack is used (for binary downloading), if none is provided (e.g. outside of Heroku)?
 DEFAULT_PYTHON_STACK="cedar-14"

bin/default_pythons

@@ -7,6 +7,8 @@ LATEST_36="python-3.6.10"
 LATEST_35="python-3.5.7"
 LATEST_34="python-3.4.10"
 LATEST_27="python-2.7.17"
+PYPY_36="pypy3.6-7.2.0"
+PYPY_27="pypy2.7-7.2.0"
 
 export DEFAULT_PYTHON_VERSION \
     LATEST_38 \
@@ -14,4 +16,6 @@ export DEFAULT_PYTHON_VERSION \
     LATEST_36 \
     LATEST_35 \
     LATEST_34 \
-    LATEST_27
+    LATEST_27 \
+    PYPY_36 \
+    PYPY_27

bin/steps/python

@@ -61,6 +61,20 @@ if curl --output /dev/null --silent --head --fail "$VENDORED_PYTHON"; then
       echo "       Learn More: https://devcenter.heroku.com/articles/python-runtimes"
     fi
   fi
+  if [[ "$PYTHON_VERSION" == $PYPY27* ]]; then
+    # security update note
+    if [ "$PYTHON_VERSION" != "$PYPY_27" ]; then
+      puts-warn "Could not find that Pypy version. Did you mean" "${PYPY_27}?"
+      echo "       Learn More: https://devcenter.heroku.com/articles/python-runtimes"
+    fi
+  fi
+  if [[ "$PYTHON_VERSION" == $PYPY36* ]]; then
+    # security update note
+    if [ "$PYTHON_VERSION" != "$PYPY_36" ]; then
+      puts-warn "Could not find that Pypy version. Did you mean" "${PYPY_36}?"
+      echo "       Learn More: https://devcenter.heroku.com/articles/python-runtimes"
+    fi
+  fi
 else
   puts-warn "Requested runtime ($PYTHON_VERSION) is not available for this stack ($STACK)."
   puts-warn "Aborting.  More info: https://devcenter.heroku.com/articles/python-support"