New Commits wont build

Hello im having trouble getting teamcity fully setup. I have managed to get the builds to work and run while its doing a brand new checkout and then building, but as soon as i do a commit and teamcity picks it up to do a new build it crashes and gives me a heap memory issue which does not happen when it does a clean checkout and pull. I would like to not have to download the repo each time fully for this to work as im using amazon servers to do it and I don't know the full cost overhead of doing that each time i want to make a commit / build.

Here is the build log
Resolving deltas 70%
[10:16:51]i:     [Collecting changes in 1 VCS root] VCS root : git fetch finished
[10:16:51]E: Failed to collect changes, error: Error collecting changes for VCS repository {instance id=21, parent internal id=1, parent
'git fetch' command failed (repository dir: <TeamCity data dir>/system/caches/git/git-122FC776.git).
stderr: java.lang.OutOfMemoryError: Java heap space
    at org.eclipse.jgit.internal.storage.pack.BinaryDelta.apply(BinaryDelta.java:163)
    at org.eclipse.jgit.internal.storage.pack.BinaryDelta.apply(BinaryDelta.java:118)
    at org.eclipse.jgit.transport.PackParser.resolveDeltas(PackParser.java:610)
    at org.eclipse.jgit.transport.PackParser.resolveDeltas(PackParser.java:587)
    at org.eclipse.jgit.transport.PackParser.resolveDeltas(PackParser.java:550)
    at org.eclipse.jgit.transport.PackParser.parse(PackParser.java:507)
    at org.eclipse.jgit.internal.storage.file.Object...
[10:16:51]E: Failed to collect changes, error: Error collecting changes for VCS repository  {instance id=21, parent internal id=1, parent
'git fetch' command failed (repository dir: <TeamCity data dir>/system/caches/git/git-122FC776.git).
stderr: java.lang.OutOfMemoryError: Java heap space
    at org.eclipse.jgit.internal.storage.pack.BinaryDelta.apply(BinaryDelta.java:163)
    at org.eclipse.jgit.internal.storage.pack.BinaryDelta.apply(BinaryDelta.java:118)
    at org.eclipse.jgit.transport.PackParser.resolveDeltas(PackParser.java:610)
    at org.eclipse.jgit.transport.PackParser.resolveDeltas(PackParser.java:587)
    at org.eclipse.jgit.transport.PackParser.resolveDeltas(PackParser.java:550)
    at org.eclipse.jgit.transport.PackParser.parse(PackParser.java:507)
    at org.eclipse.jgit.internal.storage.file.Object...
[10:16:51] : Build finished