garlic tool: check the presence of all the units

This check prevents a user from removing units between the
execution of the experiment and the fetch.

garlic/sh/garlic

@@ -105,6 +105,10 @@ do_fetch() {
     exit 1
   fi
 
+  unitNameList=$(grep '^/nix/store/.*-unit$' $experiment |\
+    sort -u |\
+    sed 's@^/nix/store/@@')
+
   cwd=$(pwd)
 
   repeat=1
@@ -113,10 +117,13 @@ do_fetch() {
     cd $exp
     test $verbose && >&2 echo "$exp: checking units"
 
-    for unit in *-unit; do
+    for unit in $unitNameList; do
+      if [ ! -e $exp/$unit ]; then
+        test $verbose && >&2 echo "$unit: missing unit"
+        repeat=1
+      else
         cd $exp/$unit
         if [ ! -e status ]; then
-        
           test $verbose && >&2 echo "$unit: no status"
           repeat=1
         else
@@ -126,6 +133,7 @@ do_fetch() {
             repeat=1
           fi
         fi
+      fi
     done
 
     if [ $repeat -eq 0 ]; then