fix overwriting relation attributes

[sickhye]

fix missing initialization

test-data

job 1--1 job_lv_group {label: "job_lv_group_id"}
job 1--1 text {label: "text_name"}
job 1--1 text {label: "text_short_name"}
job 1--1 role {label: "role_id"}
job 1--1 job
job 1--1 job

before result

  job -- job_lv_group [arrowhead=noneotee,headlabel=<<FONT>1</FONT>>,label=<<FONT>role_id</FONT>>,arrowtail=noneotee,taillabel=<<FONT>1</FONT>>];
  job -- text [arrowhead=noneotee,headlabel=<<FONT>1</FONT>>,label=<<FONT>role_id</FONT>>,arrowtail=noneotee,taillabel=<<FONT>1</FONT>>];
  job -- text [arrowhead=noneotee,headlabel=<<FONT>1</FONT>>,label=<<FONT>role_id</FONT>>,arrowtail=noneotee,taillabel=<<FONT>1</FONT>>];
  job -- role [arrowhead=noneotee,headlabel=<<FONT>1</FONT>>,label=<<FONT>role_id</FONT>>,arrowtail=noneotee,taillabel=<<FONT>1</FONT>>];
  job -- job [arrowhead=noneotee,headlabel=<<FONT>1</FONT>>,label=<<FONT>role_id</FONT>>,arrowtail=noneotee,taillabel=<<FONT>1</FONT>>];
  job -- job [arrowhead=noneotee,headlabel=<<FONT>1</FONT>>,label=<<FONT>role_id</FONT>>,arrowtail=noneotee,taillabel=<<FONT>1</FONT>>];

after result

  job -- job_lv_group [arrowhead=noneotee,headlabel=<<FONT>1</FONT>>,label=<<FONT>job_lv_group_id</FONT>>,arrowtail=noneotee,taillabel=<<FONT>1</FONT>>];
  job -- text [arrowhead=noneotee,headlabel=<<FONT>1</FONT>>,label=<<FONT>text_name</FONT>>,arrowtail=noneotee,taillabel=<<FONT>1</FONT>>];
  job -- text [arrowhead=noneotee,headlabel=<<FONT>1</FONT>>,label=<<FONT>text_short_name</FONT>>,arrowtail=noneotee,taillabel=<<FONT>1</FONT>>];
  job -- role [arrowhead=noneotee,headlabel=<<FONT>1</FONT>>,label=<<FONT>role_id</FONT>>,arrowtail=noneotee,taillabel=<<FONT>1</FONT>>];
  job -- job [arrowhead=noneotee,headlabel=<<FONT>1</FONT>>,arrowtail=noneotee,taillabel=<<FONT>1</FONT>>];
  job -- job [arrowhead=noneotee,headlabel=<<FONT>1</FONT>>,arrowtail=noneotee,taillabel=<<FONT>1</FONT>>];

[kaishuu0123]

@sickhye

Thank you for you PR.
Sorry for the delayed response.

wait a little for merge since I'm checking it now.

[kaishuu0123]

@sickhye Merged. Thanks!