obs: add --git-skip-checkout argument

Prepare to use this for wireshark, to build a branch on-the-fly that
does not get pushed to origin, with Osmocom patches on top of upstream
master.

Related: OS#2537
Change-Id: Ifc963daf51ba3542f67420daaf7b29745404a92e
---
M scripts/obs/lib/__init__.py
M scripts/obs/lib/git.py
2 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/scripts/obs/lib/__init__.py b/scripts/obs/lib/__init__.py
index edf19f4..675bcec 100644
--- a/scripts/obs/lib/__init__.py
+++ b/scripts/obs/lib/__init__.py
@@ -36,6 +36,9 @@
     parser.add_argument("-s", "--git-skip-fetch",
                         help="do not fetch already cloned git repositories",
                         action="store_false", dest="git_fetch")
+    parser.add_argument("-S", "--git-skip-checkout",
+                        help="do not checkout and reset to a branch/tag",
+                        action="store_false", dest="git_checkout")
     parser.add_argument("-m", "--meta", action="store_true",
                         help="build a meta package (e.g. osmocom-nightly)")
     parser.add_argument("-i", "--ignore-req", action="store_true",
diff --git a/scripts/obs/lib/git.py b/scripts/obs/lib/git.py
index f1ee98d..15cb276 100644
--- a/scripts/obs/lib/git.py
+++ b/scripts/obs/lib/git.py
@@ -53,6 +53,11 @@
 
 def checkout(project, branch):
     repo_path = get_repo_path(project)
+    if not lib.args.git_checkout:
+        ref = lib.run_cmd(["git", "log", "--pretty=oneline", "--abbrev-commit",
+                           "-1"], cwd=repo_path).output.rstrip()
+        print(f"{project}: skipping git checkout, current commit: {ref}")
+        return
     print(f"{project}: 'git checkout -f {branch}'")
     lib.run_cmd(["git", "checkout", "-f", branch], cwd=repo_path)
     print(f"{project}: 'git reset --hard {branch}'")

