ignore Read-only file system error on sysctl set

Signed-off-by: Peter Hunt <pehunt@redhat.com>

src/network/core_utils.rs

@@ -282,7 +282,18 @@ impl CoreUtils {
             }
             Err(e) => return Err(e),
         }
-        ctl.set_value_string(val)
+        let result = ctl.set_value_string(val);
+        // if we have a read only /proc we ignore it as well
+        match result {
+            Ok(_) => result,
+            Err(SysctlError::IoError(e)) => {
+                if e.raw_os_error() == Some(libc::EROFS) {
+                    return Ok(String::from(""));
+                }
+                return Err(e.into());
+            }
+            Err(err) =>  return Err(err),
+        }
     }
 }
 
@@ -433,9 +444,6 @@ pub fn disable_ipv6_autoconf(if_name: &str) -> NetavarkResult<()> {
                 // just ignore that case
             }
 
-            // if we have a read only /proc we ignore it as well
-            SysctlError::IoError(ref e) if e.raw_os_error() == Some(libc::EROFS) => {}
-
             _ => {
                 return Err(NetavarkError::wrap(
                     "failed to set autoconf sysctl",