git am / patch utility not applying a .patch to the correct function

[Alejandro Sanchez <alex@schedmd.com>]

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Hi,

In the SchedMD/Slurm project there's a source file with two functions
that have a very similar implementation with some slight variations,
namely _eval_nodes_dfly() and _eval_nodes_topo():

https://github.com/SchedMD/slurm/blob/slurm-20.11/src/plugins/select/cons_tres/job_test.c#L1458

https://github.com/SchedMD/slurm/blob/slurm-20.11/src/plugins/select/cons_tres/job_test.c#L2099

Before this Slurm commit:

https://github.com/SchedMD/slurm/commit/63e94c2ccbb62aea84cfb0b808761de2bb64e74c

When I attempted to git am a patch clearly targeted for
_eval_nodes_dfly(), the result shown by git show resulted in the
modified code in _eval_nodes_topo() instead. A colleague also reported
this is also happening with the 'patch' utility without git, we're not
sure if they both share any common logic or library behind the scenes.

I've attached a sequence of commands showing the contents of the patch
and the result after applying.

alex@polaris:~/t$ lsb_release -a
No LSB modules are available.
Distributor ID: Debian
Description: Debian GNU/Linux 10 (buster)
Release: 10
Codename: buster
alex@polaris:~/t$ git --version
git version 2.29.2
alex@polaris:~/t$

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alex@polaris:~/slurm/source$ cat ~/Downloads/bug11401_2011_coverity_v5.patch
From cde2c60482e704cbb9f5677ea283902c26c3765f Mon Sep 17 00:00:00 2001
From: Carlos Tripiana Montes <tripiana@schedmd.com>
Date: Thu, 29 Apr 2021 14:33:18 +0200
Subject: [PATCH] select/cons_tres with dragonfly: Fix coverity NULL dereference
Continuation of 8475ae9d77e30585ffd2733e97dfc2b5a07c7cab
Coverity CID 221511
Bug 11401
---
 src/plugins/select/cons_tres/job_test.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/src/plugins/select/cons_tres/job_test.c b/src/plugins/select/cons_tres/job_test.c
index 2d25345945..ff125fafa3 100644
--- a/src/plugins/select/cons_tres/job_test.c
+++ b/src/plugins/select/cons_tres/job_test.c
@@ -2045,7 +2045,8 @@ static int _eval_nodes_dfly(job_record_t *job_ptr,
 	rc = SLURM_ERROR;
 fini:
-	if (job_ptr->req_switch > 0 && rc == SLURM_SUCCESS) {
+	if (job_ptr->req_switch > 0 && switch_node_bitmap &&
+	    rc == SLURM_SUCCESS) {
 		int leaf_switch_count = 0;
 		/* Count up leaf switches. */
-- 
2.25.1
alex@polaris:~/slurm/source$ git am -3 -i ~/Downloads/bug11401_2011_coverity_v5.patch
Commit Body is:
--------------------------
select/cons_tres with dragonfly: Fix coverity NULL dereference
Continuation of 8475ae9d77e30585ffd2733e97dfc2b5a07c7cab
Coverity CID 221511
Bug 11401
--------------------------
Apply? [y]es/[n]o/[e]dit/[v]iew patch/[a]ccept all: y
Applying: select/cons_tres with dragonfly: Fix coverity NULL dereference
alex@polaris:~/slurm/source$ git show HEAD
commit f52a3b08cd895820c376577519c5413de7259bb4 (HEAD -> slurm-20.11)
Author:     Carlos Tripiana Montes <tripiana@schedmd.com>
AuthorDate: Thu Apr 29 14:33:18 2021 +0200
Commit:     Alejandro Sanchez <alex@schedmd.com>
CommitDate: Thu Apr 29 15:35:36 2021 +0200
    select/cons_tres with dragonfly: Fix coverity NULL dereference
    Continuation of 8475ae9d77e30585ffd2733e97dfc2b5a07c7cab
    Coverity CID 221511
    Bug 11401
diff --git a/src/plugins/select/cons_tres/job_test.c b/src/plugins/select/cons_tres/job_test.c
index acb2ae30df..bc3a81f965 100644
--- a/src/plugins/select/cons_tres/job_test.c
+++ b/src/plugins/select/cons_tres/job_test.c
@@ -2626,7 +2626,8 @@ static int _eval_nodes_topo(job_record_t *job_ptr,
        rc = SLURM_ERROR;
 fini:
-       if (job_ptr->req_switch > 0 && rc == SLURM_SUCCESS) {
+       if (job_ptr->req_switch > 0 && switch_node_bitmap &&
+           rc == SLURM_SUCCESS) {
                int leaf_switch_count = 0;
                /* Count up leaf switches. */
alex@polaris:~/slurm/source$