git-p4: auto-delete named temporary file

Take new approach using the NamedTemporaryFile()
file-like object as input to the ZipFile() which
auto-deletes after implicit close leaving with scope.

Original code produced double-open problems on Windows
platform from using already open NamedTemporaryFile()
generated filename instead of object.

Thanks to Andrey for patiently suggesting several
iterations on this change for avoiding exceptions!

Also print error details after resulting IOError to make
debugging cause of exception less mysterious when it has
nothing to do with "git version recent enough."

Signed-off-by: Philip.McGraw <[email protected]>

Author: philip-mcgraw

git-p4.py

@@ -1160,13 +1160,11 @@ def exceedsLargeFileThreshold(self, relPath, contents):
             if contentsSize <= gitConfigInt('git-p4.largeFileCompressedThreshold'):
                 return False
             contentTempFile = self.generateTempFile(contents)
-            compressedContentFile = tempfile.NamedTemporaryFile(prefix='git-p4-large-file', delete=False)
-            zf = zipfile.ZipFile(compressedContentFile.name, mode='w')
-            zf.write(contentTempFile, compress_type=zipfile.ZIP_DEFLATED)
-            zf.close()
-            compressedContentsSize = zf.infolist()[0].compress_size
+            compressedContentFile = tempfile.NamedTemporaryFile(prefix='git-p4-large-file', delete=True)
+            with zipfile.ZipFile(compressedContentFile, mode='w') as zf:
+                zf.write(contentTempFile, compress_type=zipfile.ZIP_DEFLATED)
+                compressedContentsSize = zf.infolist()[0].compress_size
             os.remove(contentTempFile)
-            os.remove(compressedContentFile.name)
             if compressedContentsSize > gitConfigInt('git-p4.largeFileCompressedThreshold'):
                 return True
         return False
@@ -3514,8 +3512,9 @@ def importHeadRevision(self, revision):
         self.updateOptionDict(details)
         try:
             self.commit(details, self.extractFilesFromCommit(details), self.branch)
-        except IOError:
+        except IOError as err:
             print("IO error with git fast-import. Is your git version recent enough?")
+            print("IO error details: {}".format(err))
             print(self.gitError.read())
 
     def openStreams(self):