[build] fix opam_retry

Summary:
Not sure what's going on but even though `set -e` is passed,
`install_opam_deps` was seen as succeeding even when the `opam install`
command failed. This prevented `opam_retry` from getting triggered (and
the error was also silently ignored).

Also get rid of a couple of useless subshells in `opam_retry`.

Reviewed By: jberdine

Differential Revision: D18615860

fbshipit-source-id: 360232623

build-infer.sh

@@ -122,8 +122,8 @@ if [ "$INTERACTIVE" == "no" ] || [ "$USER_OPAM_SWITCH" == "no" ]; then
 fi
 
 setup_opam () {
-    opam var root 1>/dev/null 2>/dev/null || opam init --reinit --bare --no-setup
+    opam var root 1>/dev/null 2>/dev/null || opam init --reinit --bare --no-setup &&
-    opam_switch_create_if_needed "$INFER_OPAM_SWITCH" "$INFER_OPAM_COMPILER"
+    opam_switch_create_if_needed "$INFER_OPAM_SWITCH" "$INFER_OPAM_COMPILER" &&
     opam switch set "$INFER_OPAM_SWITCH"
 }
 
@@ -132,7 +132,7 @@ install_opam_deps () {
     if [ "$USE_OPAM_LOCK" == yes ]; then
         locked=--locked
     fi
-    opam install --deps-only infer "$INFER_ROOT" $locked
+    opam install --deps-only infer "$INFER_ROOT" $locked &&
     if [ -n "$SANDCASTLE" ]; then
         opam pin list | grep yojson || opam pin add yojson "${DEPENDENCIES_DIR}/yojson-1.7.0fix"
     fi

scripts/opam_utils.sh

@@ -7,17 +7,17 @@
 # source this script to import its utility functions
 
 opam_retry () {
-  "$@" || ( \
+  "$@" || {
-    echo >&2; \
+    echo >&2;
-    printf '*** `%s` failed\n' "$*" >&2; \
+    printf '*** `%s` failed\n' "$*" >&2;
-    echo '*** Updating opam then retrying' >&2; \
+    echo '*** Updating opam then retrying' >&2;
-    opam update && \
+    opam update &&
-    "$@" || ( \
+    "$@" || {
-      echo >&2; \
+      echo >&2;
-      printf '*** ERROR: `%s` failed\n' "$*" >&2; \
+      printf '*** ERROR: `%s` failed\n' "$*" >&2;
-      exit 1 \
+      exit 1
-    ) \
+    }
-  )
+  }
 }
 
 opam_failed () {