From e3896043a59211017b5e7f9e94204879b2f3a12d Mon Sep 17 00:00:00 2001
From: James Bruten <109733895+james-bruten-mo@users.noreply.github.com>
Date: Tue, 17 Feb 2026 13:59:54 +0000
Subject: [PATCH 1/6] check for .git

---
 github_scripts/get_git_sources.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/github_scripts/get_git_sources.py b/github_scripts/get_git_sources.py
index 6b4d26ca..24fbc418 100644
--- a/github_scripts/get_git_sources.py
+++ b/github_scripts/get_git_sources.py
@@ -184,8 +184,11 @@ def merge_source(
         f"{source} at ref {ref} into {repo}"
     )
 
-    if use_mirrors:
-        remote_path = Path(mirror_loc) / "MetOffice" / repo
+    if ".git" in source:
+        if use_mirrors:
+            remote_path = Path(mirror_loc) / "MetOffice" / repo
+        else:
+            remote_path = source
     else:
         remote_path = source
     run_command(f"git -C {dest} remote add local {remote_path}")

From 9156e31a16be3e6b8d0631e1afffd7fbfb8db183 Mon Sep 17 00:00:00 2001
From: James Bruten <109733895+james-bruten-mo@users.noreply.github.com>
Date: Tue, 17 Feb 2026 14:21:32 +0000
Subject: [PATCH 2/6] update fetch

---
 github_scripts/get_git_sources.py | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/github_scripts/get_git_sources.py b/github_scripts/get_git_sources.py
index 24fbc418..d062d732 100644
--- a/github_scripts/get_git_sources.py
+++ b/github_scripts/get_git_sources.py
@@ -184,21 +184,17 @@ def merge_source(
         f"{source} at ref {ref} into {repo}"
     )
 
-    if ".git" in source:
-        if use_mirrors:
-            remote_path = Path(mirror_loc) / "MetOffice" / repo
-        else:
-            remote_path = source
-    else:
-        remote_path = source
-    run_command(f"git -C {dest} remote add local {remote_path}")
-
-    if use_mirrors:
+    if ".git" in source and use_mirrors:
+        remote_path = Path(mirror_loc) / "MetOffice" / repo
         fetch = determine_mirror_fetch(source, ref)
     else:
+        remote_path = source
         fetch = ref
 
+    run_command(f"git -C {dest} remote add local {remote_path}")
+
     run_command(f"git -C {dest} fetch local {fetch}")
+
     command = f"git -C {dest} merge --no-gpg-sign FETCH_HEAD"
     result = run_command(command, check=False)
     if result.returncode:

From eab491d8eec0e0a63e8d8100800d44f4bbc32c39 Mon Sep 17 00:00:00 2001
From: James Bruten <109733895+james-bruten-mo@users.noreply.github.com>
Date: Tue, 17 Feb 2026 15:07:20 +0000
Subject: [PATCH 3/6] update fetch

---
 github_scripts/get_git_sources.py | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/github_scripts/get_git_sources.py b/github_scripts/get_git_sources.py
index d062d732..d02678a9 100644
--- a/github_scripts/get_git_sources.py
+++ b/github_scripts/get_git_sources.py
@@ -184,10 +184,16 @@ def merge_source(
         f"{source} at ref {ref} into {repo}"
     )
 
-    if ".git" in source and use_mirrors:
-        remote_path = Path(mirror_loc) / "MetOffice" / repo
-        fetch = determine_mirror_fetch(source, ref)
+    if ".git" in source:
+        if use_mirrors:
+            remote_path = Path(mirror_loc) / "MetOffice" / repo
+            fetch = determine_mirror_fetch(source, ref)
+        else:
+            remote_path = source
+            fetch = ref
     else:
+        if not ref:
+            raise Exception(f"Cannot merge local source '{source}' with empty ref")
         remote_path = source
         fetch = ref
 

From aad9e2f034a58643b0db3834af912c34f611139f Mon Sep 17 00:00:00 2001
From: James Bruten <109733895+james-bruten-mo@users.noreply.github.com>
Date: Tue, 17 Feb 2026 15:20:55 +0000
Subject: [PATCH 4/6] update error message

---
 github_scripts/get_git_sources.py            | 6 +++++-
 github_scripts/tests/test_get_git_sources.py | 6 ++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/github_scripts/get_git_sources.py b/github_scripts/get_git_sources.py
index d02678a9..939b6b46 100644
--- a/github_scripts/get_git_sources.py
+++ b/github_scripts/get_git_sources.py
@@ -193,7 +193,11 @@ def merge_source(
             fetch = ref
     else:
         if not ref:
-            raise Exception(f"Cannot merge local source '{source}' with empty ref")
+            raise Exception(
+                f"Cannot merge local source '{source}' with empty ref.\n"
+                "It is likely you desire a branch name which will always merge the "
+                "latest commits to a branch."
+            )
         remote_path = source
         fetch = ref
 
diff --git a/github_scripts/tests/test_get_git_sources.py b/github_scripts/tests/test_get_git_sources.py
index ba0e1787..ea6685b1 100644
--- a/github_scripts/tests/test_get_git_sources.py
+++ b/github_scripts/tests/test_get_git_sources.py
@@ -120,6 +120,7 @@ def test_merge_sources(setup_sources):
 
     target_clone = setup_sources / "SimSys_Scripts"
 
+    # Test Remote Source merges cleanly
     assert (
         merge_source(
             "https://github.com/MetOffice/SimSys_Scripts.git",
@@ -129,12 +130,17 @@ def test_merge_sources(setup_sources):
         )
         is None
     )
+    # Test Local Source Merges Cleanly
     assert (
         merge_source(setup_sources / "merge0", "merge0", target_clone, "SimSys_Scripts")
         is None
     )
+    # Test Local Source Doesn't Merge
     with pytest.raises(RuntimeError):
         merge_source(setup_sources / "merge1", "merge1", target_clone, "SimSys_Scripts")
+    # Test Local Source without ref raises error
+    with pytest.raises(Exception):
+        merge_source(setup_sources / "merge0", "", target_clone, "SimSys_Scripts")
 
 
 def test_check_exists(setup_sources):

From e5bdb4714dfe41616a84eb4ff055df436b487e97 Mon Sep 17 00:00:00 2001
From: James Bruten <109733895+james-bruten-mo@users.noreply.github.com>
Date: Tue, 17 Feb 2026 15:26:28 +0000
Subject: [PATCH 5/6] fix syntax

---
 github_scripts/get_git_sources.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/github_scripts/get_git_sources.py b/github_scripts/get_git_sources.py
index 939b6b46..afaf3079 100644
--- a/github_scripts/get_git_sources.py
+++ b/github_scripts/get_git_sources.py
@@ -184,7 +184,7 @@ def merge_source(
         f"{source} at ref {ref} into {repo}"
     )
 
-    if ".git" in source:
+    if ".git" in str(source):
         if use_mirrors:
             remote_path = Path(mirror_loc) / "MetOffice" / repo
             fetch = determine_mirror_fetch(source, ref)

From fd412652f4c61ef03450773f67eb0425afab6b7c Mon Sep 17 00:00:00 2001
From: James Bruten <109733895+james-bruten-mo@users.noreply.github.com>
Date: Tue, 17 Feb 2026 16:19:53 +0000
Subject: [PATCH 6/6] clarify error

---
 github_scripts/get_git_sources.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/github_scripts/get_git_sources.py b/github_scripts/get_git_sources.py
index afaf3079..80374c13 100644
--- a/github_scripts/get_git_sources.py
+++ b/github_scripts/get_git_sources.py
@@ -195,8 +195,8 @@ def merge_source(
         if not ref:
             raise Exception(
                 f"Cannot merge local source '{source}' with empty ref.\n"
-                "It is likely you desire a branch name which will always merge the "
-                "latest commits to a branch."
+                "Please enter a valid git ref - if you use a branch, then the latest "
+                "commit to that branch will be used."
             )
         remote_path = source
         fetch = ref