Fix #151: git ambiguous argument error (#531)

We check if origin/HEAD is present. In case that reference is
missing, we show a meaningful error message now, with an explanation
on how to add it. Also moved find_out_of_sync_files_tracked() to
pmb.helpers.git

pmb/build/other.py

@@ -23,8 +23,9 @@ import shutil
 
 import pmb.build.other
 import pmb.chroot
-import pmb.helpers.run
 import pmb.helpers.file
+import pmb.helpers.git
+import pmb.helpers.run
 import pmb.parse.apkindex
 import pmb.parse.version
 
@@ -127,11 +128,8 @@ def aports_files_out_of_sync_with_git(args, package=None):
             git_root = git_root.rstrip()
     ret = []
     if git_root and os.path.exists(git_root):
-        # Find tracked files out of sync with upstream
-        tracked = pmb.helpers.run.user(args, ["git", "diff", "--name-only", "origin"],
-                                       working_dir=git_root, return_stdout=True)
-
-        # Find all untracked files
+        # Find all out of sync files
+        tracked = pmb.helpers.git.find_out_of_sync_files_tracked(args, git_root)
         untracked = pmb.helpers.run.user(
             args, ["git", "ls-files", "--others", "--exclude-standard"],
             working_dir=git_root, return_stdout=True)

pmb/helpers/git.py

@@ -22,6 +22,7 @@ import os
 import pmb.build
 import pmb.chroot.apk
 import pmb.config
+import pmb.helpers.run
 
 
 def clone(args, repo_name):
@@ -44,3 +45,34 @@ def rev_parse(args, revision="HEAD"):
         logging.warning("WARNING: Failed to determine revision of git repository at " + args.aports)
         return ""
     return rev.rstrip()
+
+
+def find_out_of_sync_files_tracked(args, git_root):
+    """
+    Find all files tracked by git, that are are out of sync with origin/HEAD.
+
+    In some cases (when you rename a remote or add it manually), origin/HEAD
+    does not exist. We check for that to provide a meaningful error message
+    instead of a confusing crash (see #151).
+    See also: <https://stackoverflow.com/a/17639471>
+    """
+    # Return changed files compared to origin/HEAD when it exists
+    ret = pmb.helpers.run.user(args, ["git", "show-ref",
+                                      "refs/remotes/origin/HEAD"],
+                               working_dir=git_root, return_stdout=True,
+                               check=False)
+    if ret and "refs/remotes/origin/HEAD" in ret:
+        return pmb.helpers.run.user(args, ["git", "diff", "--name-only",
+                                           "origin"], working_dir=git_root,
+                                    return_stdout=True)
+
+    # Meaningful error
+    logging.debug("Output of 'git diff --name-only origin': " + str(ret))
+    logging.info("See also: <https://github.com/postmarketOS/pmbootstrap/"
+                 "issues/151>")
+    fix_cmds = ("git symbolic-ref refs/remotes/origin/HEAD refs/remotes/"
+                "origin/master; git fetch")
+    raise RuntimeError("Your aports repository does not have the"
+                       " 'origin/HEAD' reference. Please add it by"
+                       " running the following commands inside " +
+                       git_root + ": " + fix_cmds)

test/test_aport_in_sync_with_git.py

@@ -117,3 +117,20 @@ def test_aport_in_sync_with_git(args):
     # TODO:
     # - reinstall git, but rm .git, check again
     # - remove temporary folder
+
+
+def test_ambigious_argument(args):
+    """
+    Testcase for #151, forces "fatal: ambiguous argument" in git.
+    See also: https://stackoverflow.com/a/17639471
+    """
+
+    # Delete origin/HEAD
+    aports = temp_aports_repo(args)
+    pmb.chroot.user(args, ["git", "update-ref", "-d", "refs/remotes/origin/HEAD"],
+                    working_dir=aports)
+
+    # Check for exception
+    with pytest.raises(RuntimeError) as e:
+        out_of_sync_files(args)
+    assert "'origin/HEAD' reference" in str(e.value)