ignore grep failures

build/opam-ci.sh

@@ -51,7 +51,7 @@ while (( "$#" )); do # while there are arguments left
     VERSION="$1" ; shift
 
     # Check if the pin is already set
-    PIN=$(opam pin list | egrep "^$PACKAGE[. ]")
+    PIN=$(opam pin list | (egrep "^$PACKAGE[. ]" || true))
     if [[ "$(echo "$PIN" | cut -d ' ' -f 2)" == "$KIND" && "$(echo "$PIN" | cut -d ' ' -f 3)" == "$VERSION" ]]; then
         echo "[opam-ci] $PACKAGE already $KIND-pinned to $VERSION"
     else