GitGraph: rename overlap check to shouldRerouteArrow

The function also now does an additional check to see
if source branch in overlap check is on main.

As we're no longer purely checking for an overlap and
the only use of this function is to reroute the arrows
to avoid running over commits, this more literal name
should be clearer.

packages/mermaid/src/diagrams/git/gitGraphRenderer.js

@@ -341,7 +341,8 @@ const drawCommits = (svg, commits, modifyGraph) => {
  * Detect if there are commits
  * between commitA's x-position
  * and commitB's x-position on the
- * same branch as commitA
+ * same branch as commitA, where
+ * commitA isn't main
  *
  * @param {any} commitA
  * @param {any} commitB
@@ -350,8 +351,11 @@ const drawCommits = (svg, commits, modifyGraph) => {
  * If there are commits between
  * commitA's x-position
  * and commitB's x-position
+ * on the source branch, where
+ * source branch is not main
+ * return true
  */
-const hasOverlappingCommits = (commitA, commitB, allCommits) => {
+const shouldRerouteArrow = (commitA, commitB, allCommits) => {
   const isOnSourceBranch = (x) => x.branch === commitA.branch;
   const isBetweenCommits = (x) => x.seq > commitA.seq && x.seq < commitB.seq;
   const sourceIsMain = commitA.branch === getConfig().gitGraph.mainBranchName;
@@ -395,16 +399,16 @@ const findLane = (y1, y2, depth = 0) => {
 const drawArrow = (svg, commitA, commitB, allCommits) => {
   const p1 = commitPos[commitA.id];
   const p2 = commitPos[commitB.id];
-  const overlappingCommits = hasOverlappingCommits(commitA, commitB, allCommits);
-  // log.debug('drawArrow', p1, p2, overlappingCommits, commitA.id, commitB.id);
+  const arrowNeedsRerouting = shouldRerouteArrow(commitA, commitB, allCommits);
+  // log.debug('drawArrow', p1, p2, arrowNeedsReroute, commitA.id, commitB.id);
 
   let arc = '';
   let arc2 = '';
   let radius = 0;
   let offset = 0;
   let colorClassNum = branchPos[commitB.branch].index;
   let lineDef;
-  if (overlappingCommits) {
+  if (arrowNeedsRerouting) {
     arc = 'A 10 10, 0, 0, 0,';
     arc2 = 'A 10 10, 0, 0, 1,';
     radius = 10;