Multiple CopyStatement to the same block are all applied at the same location

Current behaviour:

When multiple statements are inserted into the same block they are all applied at the location of the earliest insertion.

Expected behaviour:

Insertions should happen at the positions at which they are applied individually.

Steps to reproduce:

1) Run the following command, inserting the statement delay(); in the source code: ("35 -> 34:61")

java -cp build/gin.jar gin.PatchAnalyser -f examples/triangle/Triangle.java -p "| gin.edit.statement.CopyStatement examples/triangle/Triangle.java:35 -> examples/triangle/Triangle.java:34:61 |"

Then diff examples/triangle/Triangle.java.original examples/triangle/Triangle.java.patched -c yields:

*** examples/triangle/Triangle.java.original    2020-12-10 20:44:36.721198276 +0000
--- examples/triangle/Triangle.java.patched 2020-12-10 21:07:01.147888414 +0000
***************
*** 16,21 ****
--- 16,22 ----
              a = b;
              b = tmp;
          }
+         delay();
          if (a > c) {
              int tmp = a;
              a = c;

2) Similarly, run the following command, inserting the statement delay(); 10 lines later in the source code: ("35 -> 34:96")

java -cp build/gin.jar gin.PatchAnalyser -f examples/triangle/Triangle.java -p "| gin.edit.statement.CopyStatement examples/triangle/Triangle.java:35 -> examples/triangle/Triangle.java:34:96 |"

diff examples/triangle/Triangle.java.original examples/triangle/Triangle.java.patched -c yields:

*** examples/triangle/Triangle.java.original    2020-12-10 20:44:36.721198276 +0000                
--- examples/triangle/Triangle.java.patched 2020-12-10 21:15:36.664564081 +0000
***************
*** 26,31 ****
--- 26,32 ----
              b = c;
              c = tmp;
          }
+         delay();
          if (a + b <= c) {
              return INVALID;
          } else if (a == b && b == c) {

3) Applied at the same time, both insertions happen at the same position. ("35 -> 34:61 | 35 -> 34:96" is incorrectly applied as "35 -> 34:61 | 35 -> 34:61")

java -cp build/gin.jar gin.PatchAnalyser -f examples/triangle/Triangle.java -p "| gin.edit.statement.CopyStatement examples/triangle/Triangle.java:35 -> examples/triangle/Triangle.java:34:61 | gin.edit.statement.CopyStatement examples/triangle/Triangle.java:35 -> examples/triangle/Triangle.java:34:96 |"

The diff yields:

*** examples/triangle/Triangle.java.original    2020-12-10 20:44:36.721198276 +0000                
--- examples/triangle/Triangle.java.patched 2020-12-10 21:18:07.734566718 +0000
***************
*** 16,21 ****
--- 16,23 ----
              a = b;
              b = tmp;
          }
+         delay();
+         delay();
          if (a > c) {
              int tmp = a;
              a = c;

4) Expected behaviour: the diff should yield instead:

*** examples/triangle/Triangle.java.original    2020-12-10 21:21:21.964570109 +0000               
--- examples/triangle/Triangle.java.patched 2020-12-10 21:21:04.691236475 +0000
***************
*** 16,21 ****
--- 16,22 ----
              a = b;
              b = tmp;
          }
+         delay();
          if (a > c) {
              int tmp = a;
              a = c;
***************
*** 26,31 ****
--- 27,33 ----
              b = c;
              c = tmp;
          }
+         delay();
          if (a + b <= c) {
              return INVALID;
          } else if (a == b && b == c) {

gintool / gin