patch 7.4.1294
Problem:    job_stop() only kills the started process.
Solution:   Send the signal to the process group. (Olaf Dabrunz)

src/os_unix.c

diff --git a/src/os_unix.c b/src/os_unix.c
index a0e5ed0..17bb322 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -3920,6 +3920,11 @@
 }
 
 #if defined(FEAT_JOB) || !defined(USE_SYSTEM) || defined(PROTO)
+/*
+ * Parse "cmd" and put the white-separated parts in "argv".
+ * "argv" is an allocated array with "argc" entries.
+ * Returns FAIL when out of memory.
+ */
     int
 mch_parse_cmd(char_u *cmd, int use_shcf, char ***argv, int *argc)
 {
@@ -5107,7 +5112,8 @@
 	sig = atoi((char *)how);
     else
 	return FAIL;
-    kill(job->jv_pid, sig);
+    /* TODO: have an option to only kill the process, not the group? */
+    kill(-job->jv_pid, sig);
     return OK;
 }
 #endif

src/version.c

diff --git a/src/version.c b/src/version.c
index b5bf05e..1be6854 100644
--- a/src/version.c
+++ b/src/version.c
@@ -748,6 +748,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1294,
+/**/
     1293,
 /**/
     1292,