make `inbreeding watch` better and more robust (!136)

- early return when format is bad twice
- refactor

bins/inbreeding/watch.nu

 use consts.nu CACHE
 use path.nu [ "remove-cache-prefix" ]
 
+def pretty-hash []: [ string -> string ] {
+    str substring 0..7
+}
+
 export def main [] {
     watch $CACHE { |op, path, new_path|
         if $op != "Create" {
             return
         }
 
+        let path = $path | remove-cache-prefix
+
         let now = date now | format date "%Y-%m-%d %H:%M:%S"
-        let p = $path | remove-cache-prefix | parse "{seed}/{exp}/{id}" | into record
+        let p = $path | parse "{seed}/{exp}/{id}" | into record
 
         if $p == {} {
-            let p = $path | remove-cache-prefix | parse "{seed}/{exp}" | into record
-            return $"($p.seed | str substring 0..7)  ($p.exp)            at ($now)"
+            let p = $path | parse "{seed}/{exp}" | into record
+            if $p == {} {
+                return $path
+            }
+
+            return $"($p.seed | pretty-hash)  ($p.exp)            at ($now)"
         }
 
-        $"($p.seed | str substring 0..7)  ($p.exp)  ($p.id | str substring 0..7)   at ($now)"
+        $"($p.seed | pretty-hash)  ($p.exp)  ($p.id | pretty-hash)   at ($now)"
     }
 }