clone: use better names for temp files

Before this commit, the file names are /tmp/tmpn8smvlr8
After this commit, they are more like /tmp/hg-clone-n8smvlr8/00manifest.ndb3qj52v6,
which makes it much clearer what these files correspond to.

Differential Revision: https://phab.mercurial-scm.org/D12623

mercurial/streamclone.py

@@ -558,11 +558,15 b' def _filterfull(entry, copy, vfsmap):'
 @contextlib.contextmanager
 def maketempcopies():
     """return a function to temporary copy file"""
+
     files = []
+    dst_dir = pycompat.mkdtemp(prefix=b'hg-clone-')
     try:
 
         def copy(src):
-            fd, dst = pycompat.mkstemp()
+            fd, dst = pycompat.mkstemp(
+                prefix=os.path.basename(src), dir=dst_dir
+            )
             os.close(fd)
             files.append(dst)
             util.copyfiles(src, dst, hardlink=True)
@@ -572,6 +576,7 b' def maketempcopies():'
     finally:
         for tmp in files:
             util.tryunlink(tmp)
+        util.tryrmdir(dst_dir)
 
 
 def _makemap(repo):

mercurial/util.py

@@ -2592,6 +2592,14 b' class atomictempfile:'
             self.close()
 
 
+def tryrmdir(f):
+    try:
+        removedirs(f)
+    except OSError as e:
+        if e.errno != errno.ENOENT and e.errno != errno.ENOTEMPTY:
+            raise
+
+
 def unlinkpath(f, ignoremissing=False, rmdir=True):
     # type: (bytes, bool, bool) -> None
     """unlink and remove the directory if it is empty"""