New name suppression ignores ref changes

[1ec5]

@dgearhart reported that, in this route, OSRM doesn’t appear to issue a “continue straight” or “keep left” instruction at the Ephrata exit along U.S. 322 East near Hershey, Pennsylvania.

OSRM assumes that, because the branch to the right is a motorway_link as opposed to a motorway, this junction is an ordinary highway exit rather than a fork. The change of ref from US 322 to US 422 at this point should cause OSRM to emit a new name instruction, but I suspect that osrm::util::guidance::requiresNameAnnounced() returns false in this case:

• The name remains unchanged as an empty string on both the preceding and following motorway ways.
• obvious_change is true
• because is_suffix_change is true
• because all four conditions of checkForPrefixOrSuffixChange() are true
• because checkTable() returns true on an empty string, and decompose() returns a bunch of empty strings if the longest common substring is empty

/cc @oxidase

[dgearhart]

@oxidase here is another example

PA 283 East ends and the user should be instructed to continue on US 30 East

[oxidase]

@dgearhart #4832 adds a new instruction Merge left onto US 30 at https://www.openstreetmap.org/node/107398202#map=19/40.07055/-76.31835&layers=D

[dgearhart]

@oxidase the merge looks good - what happened to the highway suffix direction? PA 283 East and US 30 East

[oxidase]

@dgearhart locally i use a profile without cardinal directions parsing. With enabled cardinal directions the instruction is Merge left onto US 30 $east