Improved code readablity.

No functional changes.

src/http/ngx_http_variables.c

diff --git a/src/http/ngx_http_variables.c b/src/http/ngx_http_variables.c
index 669600a..2deb968 100644
--- a/src/http/ngx_http_variables.c
+++ b/src/http/ngx_http_variables.c
@@ -429,7 +429,9 @@
             return NULL;
         }
 
-        v->flags &= flags | ~NGX_HTTP_VAR_WEAK;
+        if (!(flags & NGX_HTTP_VAR_WEAK)) {
+            v->flags &= ~NGX_HTTP_VAR_WEAK;
+        }
 
         return v;
     }
@@ -494,7 +496,9 @@
             return NULL;
         }
 
-        v->flags &= flags | ~NGX_HTTP_VAR_WEAK;
+        if (!(flags & NGX_HTTP_VAR_WEAK)) {
+            v->flags &= ~NGX_HTTP_VAR_WEAK;
+        }
 
         return v;
     }

src/stream/ngx_stream_variables.c

diff --git a/src/stream/ngx_stream_variables.c b/src/stream/ngx_stream_variables.c
index 95ae12b..d1526a9 100644
--- a/src/stream/ngx_stream_variables.c
+++ b/src/stream/ngx_stream_variables.c
@@ -161,7 +161,9 @@
             return NULL;
         }
 
-        v->flags &= flags | ~NGX_STREAM_VAR_WEAK;
+        if (!(flags & NGX_STREAM_VAR_WEAK)) {
+            v->flags &= ~NGX_STREAM_VAR_WEAK;
+        }
 
         return v;
     }
@@ -227,7 +229,9 @@
             return NULL;
         }
 
-        v->flags &= flags | ~NGX_STREAM_VAR_WEAK;
+        if (!(flags & NGX_STREAM_VAR_WEAK)) {
+            v->flags &= ~NGX_STREAM_VAR_WEAK;
+        }
 
         return v;
     }